Building your own is always good, but since we're talking about prebuilt computers I would have to say Alienware. Dell, compaq, and others are very tough to upgrade and sometimes they even put funny notches in the ram just to force you to upgrade through them. They use low-quality parts oftentimes. So I would say Alienware is the best. They are very expensive but at least they use quality, name-brand parts and are as easy to upgrade as a system you build yourself. My brother bought an Alienware and all the parts are good. Western Digital hard drive, ASUS p4c800-e deluxe motherboard, ATI vid card, intel processor, Corsair XMS ram, PC Power and Cooling power supply, cooler master fans, etc.