Go for a single Wd Black 1Tb Drive.
It will give you plenty of speed while saving you cash, electricity, the PITA of dealing with a raid array and will be much more reliable than a pair of drives.
------------------------------If the automobile had followed the same development cycle as the computer, a Rolls-Royce today would cost $100, get a million miles to the gallon, and explode once a year, killing everyone inside.
PSA
Reply to outlw6669
Thanks for the reply's. It is a Gigabyte GA-MA78GM-S2H running with an Phenom II X3 720 and 4GB DDR2.
I am planning to use the WD Caviar Black for the 500GB drives and for the 1TB Drive either the Caviar Black or Seagate 7200.12 (feel free to comment which is better)
Thanks
If you plan on running RAID 0, you have one drive that fails you'll basically lose your ALL of your data. Decrease your failure points. The point of RAID 0 is for fast application retrival and writing. As a back up drive you don't want that, you want reliability. You want to know your stuff WILL be safe.