Since you state 'mirrored drives" I am assuming that you have a RAID setup?
Since you have multiple drives. Disconnect the ones that are data drives only.
Leave the mirrored or RAID drives connected. Be sure your BIOS is configured for RAID also.
Put the appropriate chipset SATA RAID drivers on a flash or external hard drive in a folder you'll recognize.
GParted can also be downloaded as a separate CD ISO image file which you can burn to a CD-R or CD-RW. Its free and a Linux based CD bootable partition program, but it will do Windows file tables such as NTFS, FAT and FAT 32.
You can also download Partition Wizard's CD ISO image. Its free also.
Wipe your mirrored array clean and start from scratch and you should be okay. Windows 7 is finicky in the fact that more that one hard drive(s) causes it to have fits when trying to install it.
Here's a good tutorial on installing Windows 7 to a RAID:
http://www.nikmakris.com/blog/post/I...Windows-7.aspx