Vista makes it possible to divide a hard disk into two or more partitions that Windows sees as separate disks. Click Start, right-click Computer and select the Manage option. Select Disk Management from the left-hand pane, right-click the disk that is to be split and select Shrink Volume. Enter a new size for the partition and click Shrink.
Now right-click the drive space marked as Unallocated and select New Simple Volume. Follow the wizard to create and format the new partition.
