|It doesn't show up in Disk Management at all? This is different from My Computer. You should see it listed as "Disk 1" or something similar. You will, at a minimum, see "Disk 0" - this is the drive Windows boots from. Gotta have at least one drive to start Windows. And beneath that should be another "Disk", which is the new one.|
Are you sure you checked for it in Disk Management, and nothing showed up there? Not even a disk with no partitions?
Do you at least see your existing disk there?
If you don't see it there, check Device Manager. See if any devices have a yellow exclamation mark or red X next to them. If so, which ones?