Windows 7 doesn't much like RAID so we see a lot of problems with it. In addition if you lose one HD you lose the entire setup so it's not even redundant.
A better option to consider is to move your data to the second HD then link it to the related Windows 7 Library - Include a Folder - Windows 7 Forums.
It's as easy as copying your User folders, then deleting their content on the source HD, rightclick the copied folder and link to library as given in tutorial.
You can also then store to the second HD a backup image of the leaner OS/Programs partition on source HD so that if it ever becomes irreparable, just boot with the Windows 7 DVD or Repair CD to Recover Using a System Image in 20 minutes - and your files are all current and waiting in place. In this way you actually have Redundancy.
See how that works for you for awhile.