If it were me I'd do this:
1) get another drive, at least temporarily
2) install that other drive, and remove the cables to your existing RAID setup (unplug them from the drives, not the board cause you want to keep them connected to the same sata headers ... probably won't matter but just to be safe that's what I'd do. And make sure you can (later) plug each cable back into same the drive it was unplugged from ... don't get them reversed).
3) Turn off RAID in the bios, install windows to the new drive, make sure it works and such, install the stuff from the mobo disc including the raid drivers and array management stuff.
4) Shut down and reconnect the cables to the RAID drives, turn RAID back on in the bios, restart, check the boot order in bios, and restart windows from the new drive.
5) at this point you may have to re-activate the RAID via the disk manager or the raid manager software that comes on your mobo disc.
6) now you should have access to the stuff on your RAID partition.
I'm not going to say it's impossible to fix your problem here w/o getting another HD, but this way I describe is likely going to be WAY safer and simpler. It's worth the investment if you really care about that data.
BTW, you should really not have set up your system like this in the first place, or if you did, you should've had a backup system going on for your 2nd partition