Roy,
I'm not a gamer but a few months ago I replaced my aging P3 machine with a reasonably high end machine from
ABS Computers.
At ABS you can pick and chose among various parts within different model lines (and they have gaming lines). For my just below "gamer machine" I priced all the parts on newegg.com, and it would have cost me more to build the same machine myself (I'm sure if I went to the lowest priced vendor for every part, the price might be lower, but now you end up with a finger pointing problem when things don't work).
The ABS machine is gorgeous, with all quality parts (including things like a top end power supply, great case, the highest rated CD burner and so on). All the documentation and spare parts come in a big binder. This company gets high ratings on CNET and PC World and so on. I'd recommend them too.
Regards,
Rick