Matty
It's not just the brand name of a computer you look at when buying a system. Your best bet is to look at what you can put into the system like the most RAM you can, a good video card, good sound card, large Hard Drives etc etc. You need to look at the specs and go from there.
Consider that any of the well know PC builders all share a great many of their components. They don't make their own hard drives, or RAM, or video cards, and motherboards; they build from stock stuff and use chipsets from NVidia, ATI, Creative Labs to name a few.