This because the card has to actually suit the MoBo
If you have enough money you should upgrade your whole computer, Ram is cheap, new motherboard(Asus is very nice in my opinion), ATI graphic cards are cheap and have good performance geforce too but they are more expensive, you can get a good AMD CPU with triple core or if you want to a quad core. There are plenty good AMD CPU's to a cheap price.
This too... Asus is good for me too. And it's always nice to have a quicker pc.
Edited:
A new mobo would suit mostly any new card as well