What Kind of Video Card should I Get?

I have an IBM ThinkCentre MT-M 8189-E8U. I need a new video card for game play. I want to get an NVIDIA GeForce card (minimum series 6), but I don't know what's compatible with my machine, i.e. PCI, PCI Express, etc...|||The whole PCI thing is your BUS type, newer computers have PCI Express most likely, if you open up your PC then you'll find what you have, in this link at the bottom will show you the differtent BUS types. This is the same Graphics Card I have but it was made by EVGA, closer to the bottom of the page will tell you lots of stuff you'll need to know "before you buy". AND, when you do buy one of these things, you may and probably WILL need to buy a Power Supply, enough power to run the Graphix card itself AND everything else that your PC is running too. For example, my PC needs 550 Watts to run, and if you have a advanced PC with Quad-Core processors and stuff like that, don't buy one of these Power Supplies from TigerDirect, a computer specialized store can order one for you probably for even cheaper and they will get you the right one too. (did I mention they can install it aswell)