This is typical of when a specific driver is needed for the IDE/SATA/RAID controller that Windows doesn't have a stock driver for. With your system, that should not be the case.
Check these things. Go into your BIOS and make sure your IDE controller is not set to RAID (I can't imagine this is the case at all).
Also, are you using on OEM or retail version of Windows 7? Did you get from a box/packaging or did you download from somewhere? If downloaded (and I assume legitimately) you may need to re-burn your DVD to get a clean image (burn at the lowest possible speed and verify).