You can use Disk Management (go Control Panel->System and Maintenance->Administrative Tools->Computer Management->Disk Management) tools to create a partition from unallocated space. Just right-click the visual representation in the lower half of the window and select Format.
Hope this helps,
I recently had a hard drive die. I purchased a new one and reisntalled windows vista ultimate. During the re install process I was given the option to create a partition. I chose to create a 25 gig partition for WVU and left the rest un partitioned. The rub is that the unpartitioned space isn't showing up. How can I "get" this space back? (it's a 1tb drive)