Video Cards....Follow

The Geforce FX 7950 is furrently the best video card around, it starts at $450. A 7900 ultra card can be had for $700. ATI crossfire cards are currently lagging behind the Nvidia cards significantly

No, there are a few considerations to check with video cards to see if they wilol work with your computer. You need to know if it is a PCI express or AGP slot (AGP is more common, PCI express is newer and faster) , and if it is an AGP slot wether it is a 1x, 2x, 4x or 8x slot. Most of the newest cards these days require pci express, but only the newest motherbaords (about the last year and a half) will have a PCI express slot. If your motherboard has a Pentium IV chip in it or the AMD equivelent, it likely at least has an AGP 4x, probably an AGP8x. If it is very new, and has a socket 775 chip it will have PCI express.

Nvidia cards are easy to set up and install. ATI cards are not as easy. With the Nvidia cards, you uninstall your video drivers for the old card and remove the hardware, then you put in the new hardware, attach any power leads that may be required, boot the computer, then load the new driver. You can see the display without the driver, it just runs slow until you get the driver installed.

Did you buy your computer already put together? if so, what make and model is it. I can probably tell you what slot it has from that.

That card is decent, but not that great. It will Run WoW though. As you can see it's an AGP 8x card, so your upgrade options are going to be limited in that respect unless you upgrade the motherboard.

If you want to stick with ATI, the highest you will be able to go is the Crossfire 1600 card, which runs about $250
http://ati.pricegrabber.com/search_getprod.php?vcode=ATI&partnum=100437510

On the Nvidia side, the Geforce 7800 is about the best you'll be able to stick in there. It's around $289.
http://www.newegg.com/Product/Product.asp?Item=N82E16814143046