The Nvidia 6600 is one of the several video card models affected by driver related issues with
The Sims 2. The chief problems are related to Bon Voyage.
I would suggest using the free download of Kaspersky AntiVirus Personal (fully functional for 30 days) and do a complete system scan, you can pick it up here:
http://www.kaspersky.com/something else you may want to do is harden you system against some of the more common menaces. It doesn't matter if you use Internet Explorer or Firefox, these are some good things to install and use regularly:
Safer Networking's
Spybot Search & DestroyJavacoolsoftware
SpywareblasterLavasoft
AdAwareA hosts file of some sort, I recomend HPGuru's available
hereThese 4 things will "harden" your system against some of the most common internet menaces.
If you do find you need a new video card, then I would say I'd have to agree with Nita-Chan, a new computer is
probably the better investment; but I'd want to know more about both the video card and the new system before I'd offer an opinion I call "confident".