|"I tried to set my computer up again with win xp pro cd"|
All you're doing is adding RAM. There is absolutely NO reason to be messing with any software or even reaching for the XP CD. This is a 100% hardware issue - put the disc away!
Post the make/model of the new RAM. We know it's 2 x 1GB DDR400 (PC3200), but who makes it, where did you get it (reputable vendor, eBay, etc), & what's the default voltage?