I want to play games like (Thief, Thief 2 metal age) etc on my current computer system which had Nvidia Geforce Ultra 8800 graphics card, etc.

The problem is that the game freezes . Tell me how to make it compatible with this system?

You newly installed an 8800 graphics card?

Are you sure the PSU can handle this?

Did you attach a direct PSU lead from your PSU to the 8800?

Dear,
There is no fault in the system all current or new games are running fine on Vista operating system. My full system specs are Intel Quad Core Qx6700 processor, MSI P6N Diamond motherboard, Apair of Geforce 8800 Ultra GPU, Enermax Galaxy 1000Watt PSU, Creative Xi-Fi Fat1lity Sound Card, Corsair Dominator 4GB Ram

right click on the game and go to properties then got go to compatability then change the drop down menu to the setting that will work