Setting up a new/test raid on ML110G1-basic

[CA1483680]

I've never set this server up before. I need to install a new set of drives, and set up server 2003 outside operating hours and then return the current set until I have it rebuilt.
This PAM (promise array) worries me. It has several "Sets" that can be defined. I just want to make sure I don't make the current set unuseable.

My question is, Do I define another set (after installing the two drives, in place of the existing drives) and the server marks them as a raid set?

Can anyone guide me through this installation enableing me to keep my current set working?
If I add another set of SATA drives, is there particular brand I should use? I currently have 2 80G Maxtors.
Are there brand & size limitations?