Since I already had Windows 7 installed on the SSD when I would change the storage mode in the BIOS to RAID from AHCI I'd get a blue screen before Windows failed to load, even after I updated the BIOS to the latest version. However, I downloaded RAIDFix
which "automatically installs missing drivers and registry entries". It seems that if Windows 7 is installed as AHCI it can run into problems when you then try to change it to RAID. After running RAIDFix I downloaded the latest Intel Rapid Storage Technology drivers and then changed the BIOS to RAID. After a couple reboots I was able to successfully set up the two 3TB drives with RAID1 in the BIOS and everything seems to be working perfectly.
Thanks for your help! Hopefully I don't have any more problems. I've set up my 1TB external drive with Windows Backup to backup the files on the 3TB so that coupled with RAID1 makes me relatively comfortable.