The answers to your questions are,
1. No, games and large videos like dvd movies, etc do not wear out a video card.
2. You will hav to open up your computer and see what kind of video card you can put in the computer. Right now there are 3 basic kinds of cards PCI( slowest of the three), AGP, and PCI-E. I doubt that you have a PCI-E but you may have a AGP slot.
Heres a AGP slot,http://www.slo-tech....01/agp_slot.jpg
About 1/4 down this page shows the different PCI-E slots and the difference between it and AGP.http://www.gen-x-pc.com/pci_basic.htm
Heres regular PCI slots with a AGP slot at the top.http://www.hwlux.de/...46-4636_IMG.JPG
Dell's usually don't have the AGP slots on the cheap models, plus PCI-E has only been out just over a year. So you might be stuck to getting a PCI video card. You will not be able to play a lot of the newer games as the PCI interface is too slow. AGP is 2(AGP) to 16(AGP 8x) times faster than PCI, and PCI-E 16 is twice as fast as AGP 8X.
3. To me the best PCI video card would be this one.http://www.newegg.co...N82E16814150040
And if you do have AGP, this one is the best.http://www.newegg.co...N82E16814130264