@asigh, yes. WD Black or Velociraptor should be perfect for 3D. I won't recommend a RAID setup for everyone as it requires some skill and some unknown operation on RAID array can cost huge data loss.
@azaad,
1) core i5 750 +Gigabyte P55+corsair DDR3
2) core i7 920 + EVGA X58 + G-Skill DDR3 performance ram
3) Phenom II X4 965 + 785G or 790GX + G-Skill DDR3 performance ram
or you can wait for the new core i7's (core i7 8xx series) that work on LGA1156 which is more mainstream than LGA1366 for current i7 processors. By going for LGA1156, you can save a lot of money on motherboard.
if you are going to work on dual monitor setup then you better pick the GPU first. for CPU, go for nothing less than Core i7.
And for GPU, my pick would be FireGL V5600 atleast.
I would advice you to do some digging on core i7, core i5, phenom II X4, FireGL, Quadro because you are putting huge amount for the rig and you better know about h/w before spending.
---------- Post added at 10:23 PM ---------- Previous post was at 10:17 PM ----------
PS: don't listen to your vendor if he says, quadro aur fire nahin chalta and tries to sell you world's best card "Geforce 8600GT"