I have a refurbished PowerEdge 2900 (PERC 5/i) that I am configuring to host five virtual Windows 7 machines.  I am VERY limited on financial resources and thus want to minimize the number of expensive SAS disks I purchase.  I plan to put two 146 GB SAS drives into a two-disk RAID array (RAID-1) for the system disk (OS).  I want to then place a single disk for each VM.  What RAID level should I use for a single disk?  Or is there some other configuration I need to use for a single disk?  Thanks for the help.