Is it posible to create a computer which can boot Windows, OS-X and
Linux and have them all use one folder for 'My Documents' and ~? And
to take it one step further, is it also posible to run every installed
os as virtual computers within every other (natively running) os?

This would allow you to:
 1. Choose which os you want to run natively
 2. Always have your documents (and settings?) in one place
 3. Run every other os virtualized with access to Documents, settings
and applications just like the native version.

Is it legally posible to sell such preconfigured pc's? Will normal
(non geeks) be able to use such a system? Would they want to?

What I already know you will probably need:
 - intel mac computer
 - apple boot camp
 - fat data partition for documents (and settings)
 - virtualisation software (vmware, parallels)
 - open source applications (they tend to use the windows registry
less and use ~/.application folders to store settings/data)

I set the price higher because I don't just want a yes or no answer,
but I set the price lower because I believe this is a fun question to
answer and maybe even helpfull for the researcher ;).

Well

  as you can see  from the comments, it is a complex question
  with experience depending on specific configuration.

  As a rule, Linux can access other OS's data, for a while at least, 
but often other OS's change they formats to prevent it.

So, it is changing constantly, it is a  tug of war.

That explains the contradicting comments.

Answer is provided by 'virtual machine' concept  (it is YES):

".. In simple terms, VMware Workstation allows one physical machine to
run numerous operating systems simultaneously. Other VMware products
help manage or migrate VMware virtual machines across multiple host
machines.

VMware Workstation has grown in popularity due to the large number of
servers proliferating in the corporate market. Transferring
workstations and servers to virtual-machine environments allows for
easier systems management, a reduction in physical footprint and
reduced need for hardware..."

http://en.wikipedia.org/wiki/VMWare
http://www.vmware.com/
also
Virtual PC and VMware: a Comparative Review - OSNews.com
http://www.osnews.com/story.php?news_id=14928

I could go on and on - but
while it may be 
"fun question to answer .."

it is still work to type and organize  it all.. 

and so, I suggest you type it in

SEARCH TERMS:  VMware

and organise it yourself.

Search terms2: VmWare - Ubuntu   

UBUNTU as a VMware host. For VMware-workstation-5.5.1-19175.tar.gz.
Steps required to get VMware Workstation 5.5.1 installed on Ubuntu
5.10 system on i686. ...
https://wiki.ubuntu.com/VmWare

It may be fun for the  asker too, to give us feedback in  a comment.

Hedgie

---

Request for Answer Clarification by seweso-ga on 29 Jun 2006 06:19 PDT

This answers about 6.27% of my question. Is the rest imposible to
answer? Is the question unclear? To much work? Because I do know this
question requires more than just a google search. Its uncharted
territory! :P

---

Clarification of Answer by hedgie-ga on 02 Jul 2006 00:27 PDT

seweso-ga

I think that extent of the answer corresponds to the price guideline
http://answers.google.com/answers/researcherguidelines.html

and also provides a practical solution - a best way how to accomplish
what you said you want (in my opinion).

It may not fullfill this expectation:
"I set the price higher because I don't just want a yes or no answer,
but I set the price lower because I believe this is a fun question to
answer and maybe even helpfull for the researcher ;) .."

 That does happens, that people give it much time that price would indicate,
 but that really is up to the researcher, is it not?

 If you want stimulate discussion, and have people volunteer ideas on 
 a topic, a usenet type forum may be more appropriate medium:

http://groups.google.co.in/intl/en/googlegroups/about.html

perhaps this one
http://groups.google.co.in/group/comp.os.linux.setup?lnk=gschg

or this 
comp.os.linux.setup - Show matching messages from this group 
Group description: Linux installation and system administration.
Category: Computers > Operating Systems, Language: English 
Medium activity, 1433 subscribers, Usenet
http://groups.google.co.in/group/comp.os.linux.setup?lnk=gschg
or

Multiboot or WMWare?  
... way to experiment with different distros, Multiboot or VMWare ...
already own version
5 workstation and GSX for Linux. If you just want to play, VMware is
expensive ...
alt.os.linux.debian
http://groups.google.co.in/group/alt.os.linux.debian/browse_thread/thread/b53ac981762e13f3/a70c9824b69297f1?lnk=st&q=multiboot%2C+linux%2C+vmware&rnum=3#a70c9824b69297f1

 So, if it is not clear what I wrote 'namely try wmware' you can ask
for clarification,
 like 'what is it, where do I get it...' but I assume you know that.

else, you can try try the groups.

some parts of your question

"Is it legally posible to sell such preconfigured pc's?  "

  are too broad to answer (it depends on  how is software you put on 
is licensed and sold)
 and call for legal advice which we do not give here. For this reason
I did not address those.

 
   You can always ask for a refund, but considering that I waited a
week to see if someone else will  pick up your question, I would not
expect, at this price,  to get an extensive research into this complex
issue.

Hedgie

I believe this is possible indeed.  I am a bit insecure about Mac, but
I know you can easily setup symlinks in Linux to read/write to
documents on your mounted fat device.  It should be possible to make
linux use your documents and settings folder as a home folder.

no its not possible because osx wont work on a windows based computers
because apple doesnt allow it and apple uses special hardware to make
sure you cant. but it is possible to multiboot windows and linux. i
personally do that myself. in linux there will be a special folder
called windows and all ur windows files will be there.. and in windows
ur just see the linux partition with all ur stuff :) .

The final answer is Yes. You couldn't do it before because of the OSX
which was based on Apple, but now with the help of Intel based Mac
"PC" you can.
So, Win-Linux and Win-Mac and Mac-Linux and viceversa could share
files and have a multiboot interface.

I can assure you that is possible since I saw it done.

Let me rephrase my question. 1) Is it posible to set the home
directory for os-x, linux ánd windows to the same shared folder? 2)
Would it be posible to let Firefox/thunderbird or other applications
use this shared folder for data/settings? 3) Is it posible to run the
other OS'es in a virtual computer (colinux/vmware/paralels) with the
same settings? (os-x and windows under linux, linux, os-x under
windows, linux and windows under os-x).

OK, thank for explaining.
1.   Nope not possible, it would have been cool; but you still can
access folders, example: from linux you can get your MP3 from the
Window's C: drive and viceversa with osx too.
2.   Well, this is negative (a no) because all 3 OS have different
platforms configs so the apps MUST follow the same configs. An easy
example is: Running .EXE on linux or osx, not possible yet (if you are
running ReactOS as linux you'll be able to do it)
3.   YES, yes and yes. It's also fun. example @:

http://blogs.pcworld.com/techlog/archives/002198.html
http://www.parallels.com/en/products/desktop/

As far as file sharing, some dual-booters (I am one but don't feel the
need, since I mostly use Linux) make a third partition formatted as
Fat 32, and that is where they place anything they want to move back
and forth, since XP can see the Fat 32 partition easily.

There are utilities which let Linux both read and write to the NTFS
file system, but they require certain expertise to set up.

Most Linux distros can READ NTFS on dual boot.  That is easy enough.

I use ext3 for my Linux partition, and if I am in Windows (see
question about non-standard pages) and need a file that is in Linux, I
use a free utility called explore2fs. It only handles one file at a
time.

The totally modern way to move stuff back and forth is called FLASH DRIVE.

But, the entire concept of three happily talking to each other as if
they were one, NO.

I think if you have a real-world need for this, it might be useful to
examine what you really need.  It is also possible to have a local
network and run the different systems, and share files that way.  I
just taught a woman engineering student here in the  mountains of
Mexico how to use Linux, because her graduation thesis was on file
sharing from a server, to keep access to one machine at a time. I am
not a network expert, but I think there are systems which let you
access files from a server on different OS.