I've exhausted all my technical "expertise" and desperately need help.

I was recently given a video card from a friend after she upgraded hers--it was better than what I had and would allow me to enjoy the game more.

I uninstalled and removed all my old video card drivers. I made sure to get the latest driver available for my new card. I even bought a new PSU to be able to support the card.

But when I try to play the game it's -worse- than ever. Before I was able to play despite having all the settings dropped and the gameplay window small. My FPS has bottomed out--it lags so bad I can barely get into the configuration window to make changes. I went from an ATI Radeon HD 5570 to a Nvidia Geforce 7025, so I just don't understand why I can't play. Is 8GB of RAM not enough? Did I do something wrong?

Can anyone make any suggestions as to help me? I'm tired of playing on my laptop and want to get back to my desktop asap!