Graphic problem

ati radeon hd4670. it constantly crashes (it just stop working, no signal at all) with some games set on high details. i ve installed vista instead of xp, bur it did not solved the problem. but now i had a new problem. movies and tv look awful. like this: freeimagehosting.net/image.php?2f2f26bfdb.jpg

i have tried with various codecs, but nothing. any help

1. motherboard: asus m3a78
2. memory: 4gb ddr2
3. psu: lc power 420w
4. processor: amd athlon 64 x2 6000+
5. graphic card: saphire ati radeon hd4670 512mb ddr3

With that picture, are you saying it is simply too zoomed in? If so, you might want to check your pan+scan options.