and you've got yourself an excellent rig with room to grow (the motherboard supports AMD CrossfireX technology as well as the newer 32nm Core i5/i7 LGA 1156 processors on the horizon).
Or you could get an AMD PhenomIIx4 955, a crossfire capable AM3 790Xmotherboard , 2x2 GB of DDR3 1600 RAM, an Antec case and a 400w Antec power supply at the same price ($415). It's not as fast as the i5 750, but if you're still using a P4 you're probably not a power user.