While I'm not an avid gamer, were I you, I'd think about spending a bit more and buying a card I'll be happy with for years to come. Of course, that's your decision. Here's what I would consider if I were choosing a performance graphics card.
MEMORY: When it comes to graphics memory, you can never have too much, especially if you're a hard core gamer. More RAM means better performance, inproved 3D texturing, and higher display resolutions. More memory also allows for smoother game play,,though anything above 256MB won't make much difference currently. You should consider moving up from a 128MB card to a 256MB card.
CONNECTIONS: The AGP bus was developed specifically for graphics cards, but it's being replaced by a faster technology called PCI Express. Both nVidia and ATI, makers of the two competing graphics-processing units - the engines that drive the cards - are supporting this new technology, which doubles the bandwidth of AGP 8x. Again, the cards are more expensive, but worth the investment if your computer will support this interface. If you have a PC which does not support PCI Express but are thinking about replacing you PC some time in the next year or so, I'd wait on buying a new graphics card and when I buy the PC, make sure it will support this interface.
DVI versus Analog: If you have (or plan to purchase) a monitor with a digital Visual Interface (DVI) connection, which provides image quality superior to the standard analog VGA interface, make sure the graphics card you purchase has this DVI connection so you can take advantage of this improvement.
I don't know what OS you are using (version of Windows), but you probably know that Windows is going to be releasing it's Vista OS in 2006. That's an OS that concentrates on gamers and graphics. It will be made for 64-bit processors and speed is the name of the game as well as the best graphics you have ever seen. If you plan to move to Windows Vista in the next year or two, this is another reason to purchase a 256MB graphics card.