What do you want the PC for? Unless your going to be running massive video editing, photoediting, software etc. or gaming I personally don't think you need a Quad Core processor, or a PC with such high specs. Unless you've got your heart set on getting one! If your looking for an everyday home computer I wouldn't spend £1100. You can buy a perfectly good modern PC for £600.
Anyhow, If you are into gaming and editing software, they are both great PC's. However, I would wait a few months and perhaps think about getting a newer and better graphics card. There is rumoured to be a upgraded 8800gts and a 9800 card. But as I say If your looking for an everyday home PC for the family to use, I wouldn't get such high specs.
Ignore me if you are wanting a high end multimedia PC though!