If you buy a PCI card you won't have to worry. You'll have to determine whether or not you have an AGP slot. Take your cover off and see if there is an empty brown slot on your motherboard. Here are 2 you can pick up almost anywhere. Search online to get them cheaper.
http://www.bestbuy.com/site/olspage.jsp?...d=1140392154117
http://www.bestbuy.com/site/olspage.jsp?...d=1130987962366