How big is your power supply unit (psu)? If it is only 300w, then I would suggest this graphics card:
http://www.amazon.com/EVGA-01G-P3-N9...dp/B001EH8FZA/ Its $60, and its the one that I have.
If you have a bigger power supply, like 350w or more, and you want to have a slightly stronger graphics card without spending too much more money, you can get the step up version of the previous graphics card for only $5 more ($65):
http://www.amazon.com/EVGA-01G-P3-N9...dp/B001ENI3C4/
If you want to spend a lot of money for a really high performance graphics card, you can spend $150 for this one:
http://www.amazon.com/EVGA-nVidia-Ge...dp/B001OV7MIC/ but I doubt you will need that much power. There are also graphics cards that cost $300+, and can run any game on the highest graphics possible, but I have the one that I gave you in the first link and I can run basically any game on highest with just that one.
Here is the xbox 360 controller for the PC:
Wired Controller ($28) -
http://www.amazon.com/Xbox-360-Controller/dp/B000B6MLTQ
Wireless Controller ($57) -
http://www.amazon.com/Microsoft-Xbox...dp/B000KA5T6A/
Its probably worth it to just get the wired one, but if you want wireless freedom you can pay the extra $30. All you need to do for both of them is just plug it into your computer and download the windows drivers for free, and they should work. You can customize the controller buttons on any PC game that you play.
If you don't know a lot about computers, you should have someone else install the graphics card for you. Its not too hard, but if you don't know what your doing you could break something or not do it right. It took me about 30 minutes to install mine (it wasn't fun, I kept thinking I would break it) but it works now and its definitely worth it in terms of gaming.
Also another good thing about PC games over console games is that every new game costs only $50 for the PC, where as for Xbox 360 and PS3, the new games cost $60.
Check out my best projects so far and please comment:
Tic-Tac-Toe 2.0 ................... http://www.alice.org/community/showthread.php?t=3548
Alice Paint ........................... http://www.alice.org/community/showthread.php?p=23408
Real-Time Clock .................. http://www.alice.org/community/showthread.php?p=12725
Maze Game ......................... http://www.alice.org/community/showthread.php?t=4301