Hard Drive Edit Backup FCP

Hi Everyone

I'm investing in a Apple Mac Pro 2 x 2.66Ghz Nehalem, 12GB Ram, 1TB System Drive and 3 further 1TB drives (i.e. to fill all 4 bays).

I already have 1TB MyBook, and 750GB MyBook, External Drives.

I won't be getting a Raid card yet for my setup - I'm not yet sure how a Raid setup works yet. Once I get the knack of using my Mac Pro I will explore the possibilities of a Raid setup.

Hopefully I can use Time Machine also.

I'm not sure about which of the 1TB drives I have I should ideally use as my scratch disk. Previously I've just used my 1TB MyBook external drive.

Before I embark on editing my first project in FCS using this new setup, can anyone please offer any quick tips about how I might best use my hard drives for sufficient backup?

Any tips whatsoever appreciated - it would be great to have peace of mind from the offset that anything I edit is backed up.

Thanks in advance

Peter