Once you have partitioned the hard drive, as time goes on, the free space will be less and less, and then you may have to repartition this hard drive. However, there are some limitations with Windows build-in disk management. You may unable to not move the unallocated space to extend the non contiguous partition or could not create more partition. Once you have created 4 primary partitions on MBR disk, you could not create more partitions. The solution is to convert one of the partitions to logical. But Windows will not allow you convert it without data loss. In Windows 7/8, it allows you to create more partitions unless you convert this disk to dynamic disk. However convert to dynamic disk is not a good solution.
Good news: we are having an special event on 0:00 10 July to 24:00 12 July (GMT +8 Time Zone). You can view more details on this site: http://www.disk-partition.com/specials/pa-lite.html . At this very time you could download Partition Assistant Lite Edition then resize partition without limit on Windows server OS. To say more specifically, you could extend, shrink and move partitions without limit, thus you can smoothly resize server partition.