It's a Windows thing.
Windows likes to create buffer space in the beginning and/or end of a drive to use for tasks like creating Dynamic Disks. If you formatted the drive using Disk Management or the Windows install DVD then that is where it came from.
You can use Partition Wizard Bootable CD to reclaim the space. A very easy and safe operation, provided you will never use Dynamic Disks.
Partition Wizard Bootable CD allows user to manage partition directly with partition manager bootable CD.
Hope that helps.