If you are vast on budget I'd go for a Medion. The germans sure know what they are doing, and the prices of their machines are just great.
Last one I saw had this:
- Core i5 3450 [3rd gen 4 cores etc]
- Some Asus motherboard with USB 3.0 PCI 3.0 x16 some other PCIs etc
- 8 GB Ram low case latency, high freq (1600 Mhz iirc) [You'll fly with this]
- 64 GB SSD for OS + 1TB HDD
- Hot Swap [to change HDDs while active]
- Nvidia GTX 550 Ti [Not the best, not bad either, you'll pretty much run all games on medium at least]
- Blu Ray Unit [Pretty awesome to have this]
- Corsair 450W PSU [More than enough Watts, enough amps on the 12V rails etc]
Price: 650€
Best stuff for the best price hands down. Honestly, I was really tempted to buy that one, unfortunately I was low on budget at the time.