why do you want to upgrade?
are these your components?
Intel Pentium 4 650 Processor
3.4GHz, 800MHz FSB, 2Mb Cache
2048MB DDR RAM
360GB Hard Disk Drive
M-F Dual Layer DVD-RW / DVD-ROM Drives
256MB ATI Radeon X600 Graphics
4 USB connections
4 PCI Slots
Microsoft Windows XP Home Edition
19" TFT Flat Panel Monitor
if so.. i'd only recommend upgrading if you're a gamer. if you want better performance in games, you can get a much better video card... depending on how much you want to spend.. looks like you have a pci-express slot which is good. if you do get a new video card, you might also need to replace your powersupply.. depending on what type of PSU it is...
so ya.. tell us why you want to upgrade, what you do with it, and how much you want to spend...
(again.. if you don't game.. don't upgrade..)
"Is virtue a thing remote? I wish to be virtuous, and lo! Virtue is at hand." -Confucius