My computer system came with windows Xp X64 Edition. Can I downgrade
to Windows XP Professional since there aren't many drivers out there
for it. Then I can revert back once there are. I need to use my $400
scanner(epson perfection photo 3200) which has no driver for X64. Also
I have an upgrade cd for windows Xp professional will that work to
downgrade.

I do not believe you can downgrade or revert.  You would have to do a
reinstall of Windows each time.  The upgrade cd may be a problem. 
Sometimes the upgrade CD requires there to be an OS on the machine to
install.

Is there any way to get around the driver and use the scanner. Windows
already searched for it and can't find it. I know on printers you can
set it up as a network printer and it works they work. Is there
something similar?

What would happen if I put the XP Professional upgrade cd in with X64
already installed? Will it not even let you try?

There are some scanners that are networkable that will allow you to
scan a document and then email you the result.  Your scanner is not
one of these.

As for what will happen if you put in the upgrade cd, try it.  It
won't automatically upgrade your system or anything.  If I had to
guess, I'd say it will tell you that Windows XP is already installed.

No you cannot downgrade the installation, but I may have a workaround
for you.  This has worked for me in the past in some situations and it
may help you.  Fair warning though, this could give you some problems
if things don't go right.  If you have no other options, you may want
to try it.

First, install the driver for the scanner.  Click on Continue Anyways
on any warnings you get about the driver possibly being incompatible. 
Next, locate the executable file (.EXE) file for the program you use
to interface with the device.  Right click on that file and click on
Properties.  On the window that comes up, click on the Compatitibility
tab.  In this tab, click on the checkbox for 'Run this program in
compatibility mode for:' and select Windows XP first.  Click Apply
then OK at the bottom of the window.  Try running the application and
see if the scanner works with the program.  If it does not, you can
try running it under the OS options in the compatibility list, but
they may not work for you either.  It's pretty much hit or miss
unfortunately, but it's a great way to get programs and devices to
work if you have no other options.

If this doesn't work or you do not want to take the risk, I would
backup everything and rebuild it under WinXP.  I hate to only provide
two options for you, but I don't believe you have any other
alternatives as you cannot go backwards on most OS installations. :(