Just bought the new Seagate 2Tb SATA 3.0 drive. It shows up in my BIOS and device manager, albiet with only 4000MB of space, but not in my computer. I tried to format the drive, but it does not show up in disk manager either. According to Windows 7, the device is working properly and drivers are completely up to date.
I've tried switching around SATA ports, but that didn't help. I would try a different cable, but I really don't see how that would help in this particular situation.
In Device Manager right click on it, see what options come up, if one is initiate click on it.
I remember one time I had to initiate the drive first, but I couln't remember if it was Device Manager or Disk Manager.