Unfortunatly i bought Fallout 3 today on steam and unfortunatly, the damn thing wont run, as when i click Play on the launcher i get a message from windows saying Fallout 3 has stopped working.

My specs are

AMD Phenom II quad core 3.20ghz
4GB ram
Nvidia Geforce 210 512mb

I've heard there has been problems with quad core processers, is ther any thuth to this?

More than anything else, you chose to buy a graphics card that is cheaper / slower / weaker than the current crop on Integrated chipset video chips. In this side by side comparison, it doesn't appear to be as truly bad as it really is:

http://www.gpureview.com/show_cards.php?card1=621&card2=180

It's really very far below the minimum card needed. Beyond that, I have heard that some AMD Quads have been considered less than fully compatible with Bethesda's games.

I know the video card is lousy but ive manged to run newer games like Deus Ex Human revolution and had no problems.