In fact, there are two ways to resize Windows 2008 partition:

1.Disk Management snap-in: With Shrink Volume function, you cannot decrease the allocated space beyond the point where the unmovable files are located. Extend Volume function can only extend partition into contiguous unallocated space which is at the right side of the partition (behind the partition).

2.Partition Magic Server 2008: http://www.partition-magic.org/windows-server-2008/windows-server-2008-resize-partition.html