I went with 4 gigs of RAM to preserve the dual channel function(matched sticks in all slots). Windows actually recognizes 3.2 gig so there is still a performance boost over the 2 gig I started with and it was just too cheap to pass up.
actually.. you can get XP 32 bit to recognize 4G of ram.
without doing this, XP uses the rest of the RAM for page file.
think of page file allocation as the same thing as L1/L2/L3 cache on the mobo and processor, only page files load "pages" of code in very large chunks, where cache only handles up to 8-16MB.
you also will have to max out your RAM to start using PF for the processor.
also, cache is quicker.
BUT, if you would rather use the RAM-stick as its function of storing and recieving data, you can modify the BOOT.INI file by putting the command /PAE to utilize 4G of ram and not ~3G with 1G of wasted PG space.
PAE stands for parameter array - array's the address bus (not the data bus) for RAM going to the processor.
how do i know this? because ive done it and it works. running close to the same system myself - AMD 6000+ overclocked to 3.19G, 4G RAM - XP-32bit - twin raptor western digi's running RAID 1.
did it all for around $800 shipping and all.
god i love christmas sales xD