Darth Tyranus,
Free yourself from the chains and oppresion of pre-build PC's, build your own Rig. The sage advice from all the previous posts should be heeded. Even if you have money being extruded from every orifice of your body, consider the principle of some bonehead taking advantage of you and ripping you off.
There are many quallity, knowledgeable and helpful people that frequent this forum. Ask and you shall receive...
Check out NewEgg, ZipZoomFly or even TigerDirect. If you are uncertain as to what hardware best suits your needs or if there are compatability questions....just ask. I did, they freed me from the Matrix of Dell.
For H2O cooling check out DangerDen, Petra's Tech Shop or Swiftech.
If you build your own Rig you will be your own tech support, if you require further support you will find it at this forum. In addition will have an intimate knowledge of your Rig and the DIY pride will liberate you.
I had several issues with my build, but all the questions were answered here.
If after you have given it some thought and still want to buy a pre-built PC, that is your right. Maybe check out Falcon Northwest, though you might want to get some feedback.
Om mani pad mi om