OS = Operating System (Windows 98, Windows XP, Linux, etc.)
For your video card...go to Start > Programs > Accessories > System Tools > System Information. In the left panel, click on the
+ next to Components and then click on Display. In the right panel, it should display the name of your video card. This information can also sometimes be found printed on the front of your PC.
As for your game...have you tried reinstalling it? It sounds like certain files may have been corrupted, based on your description. First, make sure you have the latest patch. If that doesn't work, you may need to reinstall. This will be a bit of a pain, but I would suggest backing up your savegame files, uninstalling The Sims 2 (and any expansions), running
Cleaner and
Issues on
CCleaner (install without Yahoo! toolbar), rebooting, and reinstalling your game. Phew.