I'd go for something like this but I'm really no expert at picking the right parts in a rush;
http://img718.imageshack.us/img718/1893/ebuyerpc.png
That gives you the potential to get a totally awesome graphics card in the future and upgrade to Blu-Ray. The motherboard seems pretty futureproof supporting upto 24GB of RAM so that can be easily upgraded and 650W should be enough.
- Excellent CPU
- 6GB RAM should be plenty, easy to upgrade should more be needed
- 30GB SSD, install your OS onto it and you'll boot very quickly :D, for all your other files there's a fast 1.5TB HDD.
- Graphics card should have no trouble with HD although for some mad gaming you'd probably want to upgrade.