Alienware M9700 video cards make laptop lag

Hey guys, I gotta a problem. After months of trying to get my video card drivers to work with windows 7, I finally made it happen. After that happened the laptop started to be slow and laggy. There was no lag problems while the video cards weren't installed. I'm saying like YouTube loads slow, so the audio plays fine and video skips constantly or freezes. Scrolling and load times for the browser are skippy and very slow, respectively. I don't know what I should do about this. I have 2 Nvidia 7900gs currently going with the temp. at 74C. That's too hot, so I think that has something to do with it. Thanks for your time, and your help!

EDIT: I forgot to add, when starting up sometimes Windows will freeze and I have to hold the power button to shut it off. and other times, when it's loading up the monitor shuts off and about 2 minutes later it will turn on and then windows will show up and finally load.