Hi
I think you may want to look at
Control Panel - System and Security - Admistrative Tools - Computer management
and look in Storage/Disk Management, you might see it in there as it wont' be initialised, normally when you mount a new drive windows will "install" the hardware drivers and ask you what you want to do with it, but if you or the machine missed that part out, you go into computer management to sort it.
The other thing, is, did you install the SATA drivers from the CD or have you checked for updated drivers on the gigabyte site?
Good luck