As per Microsoft site, minimum supported RAM by XP Professional is
64MB and minimum recommended RAM is 128MB. With 64MB, it may limit the
According to this site also, 128MB is the recommended memory for XP.
Now if you upgrade your system from 256 to 512MB, XP will still use
the minimum RAM but if you are adding any additional software like XP
Office (additional 8 MB of RAM for each Office application, such as
Microsoft Word) or something else, then definitely more RAM is
required. However, XP will not consume more RAM if you are adding more
RAM to the system. Infact the performance will get improved to an
extent with this increase.
Check this out for XP
For Office XP Developer System requirements
Search term used:
RAM used by XP
I hope this helps. Feel free to ask for a clarification and if you are
satisfied with this answer, then do rate it.
Clarification of Answer by
26 Jul 2002 13:45 PDT
Hello and thanks for giving such a nice rating.
The only reason I'm able to foresee is that when you had 256, it was
using some paging file or in other words Virtual Memory for your
software. Now when you moved to 512, instead of using the virtual
memory, it used the added 256 MB of RAM, as a result you still see a
less memory instead of 256 MB. As more memory is used and comes to a
full, system will again start using virtual memory to keep the things
working. To see how virtual memory works, check this one. It has a
nice explanation about how it works and why it is used.
I hope this will help in solving your mystery.