+1 for software-RAID...
Note: for a RAID to be truly redundant with only 2 disks, RAID 1 (known as mirroring) is the only option. Any other config risks loosing your data when (not if, because it'll happen!) either disk fails.
My advise: install Debian on a single disk, then install Webmin and use its web-interface to configure your RAID. It's easier, especially for novices
A better setup would be a separate system disk (SSD!) and the disks you have as RAID 1 data disks. Choose a 30-40 GB SSD, these are relatively cheap and large enough to hold the operating system. It's pretty much what I've done on my desktop and servers