What`s better between Caviar Black 500 vs Seagate Momentus 750?

Hello, i`m going to build a new high end gaming computer.

I`m going to buy only 1 Hard Drive as main system hard drive.
I want to buy one hard drive and then buy ssd.
What`s the better choice between Seagate Momentus 750GB or Caviar Black 500GB.
These Hard Drives are different Momentus is Hybrid HDD\SSD and Caviar Black is HDD.

My Setup:
i5-3570K
Asus Maximus V Formula
Asus GTX 680 4GB
Corsair HX 1050W Gold
Hdd?
SDD (in future)
CM Storm Trooper