I agree with above. Also keep an eye on Origin as they will give away older games for free. I still haven't played bejeweled yet, but I know it's there if I want it.
But I want a demo of a game that have next generation graphics.I went to steam but there are no demos that have next generation graphics.
Steam has a lot of Indie game demos so you have to search for long enough until you come across a demo of a good game.