Guideline: Gaming-PC for your budget!

[KaBooM]

Yea I have 4 GB of RAM, as for what I want to play... Deus Ex 3, MW3, Assassins Creed 2, Mafia 2, CoD BO, Crysis 2, are the ones I want to play the most, you said there are other cards in that range of price... less than 100 USD? Which cards can you suggest for me?

I didn't look up the price for that AMD 7770 before I put it, I can't afford it, unfortunately.