Build your own. Seriously, it's not that hard, with a bit of research. OK, alot of research, but you learn alot along the way and you can save alot of money. You don't get a warranty, but in the process you also learn what you need  to do your own repairs.

And if that's not an option, pick out the type of hardware you want, buy it all online (newegg.com is an excellent resource) and coordinate with a reliable and licensed local shop which will help you decide, and assemble it for you.

There's a good reason why OEM machines are inexpensive, and it's not just because they do so much business - they tend to use cheap parts.

IMO, anyone who's really into computers should learn how to build their own, if they can afford it.

EDIT:
Yeah, what svdl said above. Although, IMO, the Q6600 is a bit dated these days and for only a little more money, you can get much more CPU. The 9550, for example, which is 45nm.