HP Pavilion P4 2.4GHz 256MB 60GB CDRW DVD WinXP ($699)
http://www.compgeeks.com/details.asp?invtid=CMHP7965-60
eMachines Athlon XP 1900+ 80GB 256MB CDRW DVD WinXP($549)
http://www.compgeeks.com/details.asp?invtid=T1980
HP Pavilion 502N Celeron 1.3GHz 128MB/40GB/48x CD/Windows XP Home ($398)
http://superstore.ubid.com/is-bin/I...gb&CatalogCategoryID=VcvAqCo4B4IAAADxSOzZh3Ag
Think Box Ultra Gamer Standard, AMD XP 2200+, 512M DDR400 Memory, Geforce4 128M Video Card, DVD/CD-RW, 80GB. ($1020)
http://directron.com/system1004.html
4 systems I found in 15 minutes or so, the last one is a custom gamers box. It all depends on what you want to do with your computer, The fastest processors now hit 3gig, which makes your computer a dinosaur, but if it still does everything you want it to do it is a good computer. I run a Athlon 2100+ with over 700mb of DDR a Radeon 8500 and a four hard drive raid set up. But the computer I use for the internet is a old IBM workstation (P3 933, with intergrated everything), the IBM is just more reliable than the hot rod I tinker with (and with all of that it's now 6 months out of date).
For your situation, (faster CPU, bigger HD, more Ram and a CDRW) you are building a new computer in order to upgrade. Build new or buy new, either way the Video card is ok and at least two of the machines listed above could probably be upgraded with your video card and memory to pretty good machines. I think the emachine up there has intergrated graphics, and the gaming machine is using DDR memory. With a little time a some research you can make a pretty good machine or you can find a decent machine that fits your needs (my machine above was under $1000 and I bought all the parts when they were top of the line, the IBM was $500 a year and a half ago, I've got a emachine 400mhz sitting in my floor that I paid $60 for 6 months ago).