Windows 7 Gaming Lag

I just upgraded to windows 7 from vista a few days ago, and none of my games run properly. I tried to run Assassin's Creed, but it would stop and start several times a second. With very slow gameplay and the mouse lagging constantly, I can't actually play any games. I've managed to find out it's because I need various drivers for windows 7, but I can't find out which ones I should get.

I'm running this on a laptop, a Lenovo T500, and the specs are:
Intel Core 2 Duo CPU 2.26GHz
2.00 GB of RAM
32bit operating system.