External Hard drive queries ( RAID?)

[Bly]

Where to start . . .

Ok, so I am running 10.5.8 and want to upgrade the OS X ( about time ). My imac is having issues, so before I get into that, I want to back up to an external HD then wipe my imac, get rid of whatever problem is preventing my upgrading and reinstall.

1) I've been kindly gifted 2 x 1 terrabyte HDs in an enclosure that I want to set up for RAID. How should I format these? I've attached an image off the back as it has no trade marks or any other identifying features. They appear in Disk Utility as "Oxford Semiconductors" but the website does not list any external HDs in their product line.

2) I want to use these external harddrives as my core drive and a back up. Would RAID even be appropriate? I want to use my imac for my applications only - all my files on the external HDs.


Have attached images

I'm really flummoxed at where to begin - any pointers would be most gratefully received

Bly

iMac 10.5.8 3.06 GHz Intel Core Duo 2 Duo
4 GB Ram 800 MHz