What to put on what HDD for best performances

Hi,

A New HDD just fallen on my lap recently, I'm new into Premiere and I wished to use it for my video edition.

Here my current Spec:

CPU  I7-2600K @ 4.6Ghz

RAM: 2 * [ RipjawsX ] F3-17600CL7D-4GBXHD (8 Gig total)

Motherboard: GA-P67A-UD5-B3

Hard Drive: 2 * Seagate Barracuda 7200.12 500GB in Raid 0

Graphics Gigabyte GeForce GTX 570 Fermi Windforce

The new HDD: is a ST 7200.14 500 gig.

Right now, because I have no choice, all is on the RAID 0 array.

I want to know for what / what to put on the new 500 gig HDD I've got.

Best regards,