If you are looking for a new rig, not just a CPU, I will recommend these guys.
http://www.xidax.com
I just bought a new rig from them and the customer service was outstanding. I spent 2 hours on the phone and went through every single component on the machine with their sales manager, with his advice on where I could save money and where I should spend it. I bought a monster of a gaming PC, and you may not be looking for all that. They do sell cheaper models than what I bought, but not sure how low-end they go.
I priced out the parts separately and it was nearly the same after shipping, and buying separately didn't include the OS — or the lifetime warranty.