Alienware has just launched the new X51, which is a console sized gaming PC.
X51 comes with either NVIDIA’s GeForce GT 545 graphics in the cheaper model, or GTX 555 in the top end specs. Prices start at £699 (no US price has been confirmed yet) which is just ridiculous for what you're getting.
Everything is upgradeable just like a regular PC, but will it run as quiet?
If you're interested in buying one (may god help you), you can get them here, and customize them.