install second hard drive

1) If you are using a software RAID, you'll need to configure that via mdadm

2) You said that "install a second raid hard drive" and I think you are confusing things because installing another hard drive does not automatically equal a RAID setup. A RAID setup involves multiple hard drives which are configured to a certain way be it RAID 0, 1, 0+1, 1+0, 2, (uncommon), 3, 5, 6, etc.

3) If you launch gparted, the second drive isn't showing up in there at all?

4) Avoid Non-LTS releases of Ubuntu as their source comes from debian-unstable whereas the LTS releases come from debian-testing. The Non-LTS releases of Ubuntu tend to be very unstable for this reason; which also makes sense because these versions of Ubuntu are really the betas for the next LTS version (12.04); so I highly recommend staying with a version of Ubuntu which has more stability and which also has a much longer support lifecycle, along with stability when compared to the non-LTS versions.

5) I get that you want a second drive, but I'm not sure if you want (or need) a RAID setup. Yes, it's good to have another hard drive internally for a backup, but you should also backup to an external hard drive as well as to an online storage space. As for WHAT you back up, be it the entire hard drive or just your personal files, that's up to you.