With windows vista will you be able to play old games that you were able to on windows xp, like the Sims2?
Yes... and no. Most games will run on Vista, though if there's any issues at first, your best bet is to make sure you've also installed DirectX 9 runtime files. There will be some games that do not recognize those files on Vista even though they've been installed, and will either run in a limited "mode", or won't run at all. So far, I've only run into one game, Gutterball 2 from Reflexive, that won't run on Vista. The older the game, the more likely you'll run into issues playing it.