Have you looked at
Control Panel/Administrative Tools/Computer Management/Storage/Disk Management
That will tell you exactly how your disk is set up. There may be more than one partition and indeed the other partition could be hidden.
Suspishio
My advice is at your risk
Qosmio G50-10H; T9400 2.53GHz Core 2 Duo; 4GB RAM; Vista HP (32)
nForce 680i LT; Q6600 Quad Core 2.4GHz; 8GB RAM; XP Pro (64)
Dell XPS M1710; T7200 2GHz Core 2 Duo; 2GB RAM; XP Pro (32)