I had this problem too. Silly people, I had the exact same harddrive, they ship it to you without formatting it at all.
I had this problem a few weeks ago, and I'll tell you exactly how to solve it. ^_^ It won't show up in 'My Computer' unless it is formatted properly.
First off, hit Run. Then type in 'compmgmt.msc'. Very simple, ne~?
Next click on 'Disk Management'.
If you've plugged in your harddrive to the compie, there should be something there about your harddrive. Weither it be healthy or unpartitioned, it should be on the list near your other harddrive(s).
Right click on it and hit 'Format' or 'Create Partition', I can't remember which one I hit, but either will do. This should most certainly work.
I just can't believe they've been shipping these lately unformatted. >< People these days get lazier and lazier~
Hope this solves your problem!
~Mip