i would say if you want to play games with max your going to have to spend around 700$ i dont think HTPC is what your going to want at all for games. i think we will need like how big you want the screen thing to be, how high you want the game to play, screen resolution, blu ray, etc.
Edit: After looking at your post on the noobie help thread i would say you want something pretty top tier the asus G72GX-RBBX05 seems to have solid specs and the gateway P-7915u FX, im not sure what country you are in but best buy has both of these in stock. someone typed up the differences on yahoo answers so id recommend you look here. the price of the asus is actually a 50$ less now than the gateway so i guess id recommend that.