My dad has the same computer, Dimension 2400 or 3000, right? Oh man, I won't buy another Dell, not after that, consider yourself lucky. You're running 512mb, he was running 256mb, talk about slow.
I pulled out that Dell installed crap and put in 2 slides of 512mb, and reinstalled windows. SAVE UR NEEDED STUFF
Processor is too hard to upgrade on that thing, not worth the trouble. the heatsink and cover is weird. I finally got the cover off and I found more dust than I have ever seen in my life.