Interestingly enough, my friend was having difficulties with his gaming laptop so he decided it was time to build a computer. It still had to be portable, but be more powerful than his existing hardware. Budget was around $800. This is what we decided on in the end.
Not the nicest looking case, but it is small and packs in plenty of features. The i5 750 is a great mid-range processor for gaming. The original plan was to go with a HD5770 but he decided to upgrade a little at the last minute, hence the HD5830. All the other parts were chosen based on afford-ability without sacrificing quality. A nice bonus we tied in was the ability to later add in a second graphics card for ATI Crossfire thanks to a compatible motherboard and a decent power supply.