I recommend a Core 2 Quad,Intel-X48 based motherboard(x58 is coming also),4 GB DDR3 (or more),a Geforce GTX260 or 280 graphic card as main components,a 10000rpm HD for data storage,and a solid state disk SSD for the OS (fast access).
Just keep in mind that the price for this (my dream...lol!) config can go pretty high,especially the GC.
I'm planning to assemble a computer,and let me tell you that choosing the right parts isn't an easy task.