Here is a little info on your card:
http://www.devhardware.com/c/a/Video-Cards/PowerColor-X1300-512MB-GameFX/It's an entry level card PCIe X 16 slot and 300w power supply required. The real factors in choosing a graphics card are, how much do you want to spend and, what do you want to do with it. The card you have could go in any tower with a PCIe x 16 slot except for maybe mini's, and more than likely, would not require and uppage of power, meaning replacement of power supply(greater). I personally like the Radeon HD cards because they are capable of excellent graphics and will provide sound as well. If you are into the gaming scene, this card will not provide the high end requirements you are looking for but, then again, you woukd also have to up your power supply, to meet the needs of a higher end card. There are alot of different manufacturers of the cards but, basically only two that make the chipsets, ATI/AMD and Nvidia. To stay in the same power range your in now you would go with something like this:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125377Newegg is a good place to view different cards and their requirements and, if you chose to upgrade even further, they have the power supplies, etc. A card in your range would probably be in the 40.00 to 100.00 price range. You can spend a heck of alot more money on a card and, you can also double and join certain cards to gain the speed, etc., it all depends on how much you want to spend and how much work you want to do to your system. One thing you would want to consider would be a card that has Windows 7 or, at least Windows Vista support.
