Resizing partitions

1) run chkdisk on your c:
2) defrag your c:
3) boot from an ubuntu or fedora liveCD
4) use the built in tool Gparted to resize your partitions. all done.

If you're using Windows 7, you can use the built-in partition manager. Type "disk management" into your start menu search field and hit enter. Now you're in the Disk Management console. Since your D: partition is empty, just delete the D partition. Now you can just shrink your C: partition to the desired size and reformat the remaining free space back into your D partition.

As mentioned above you'd better defrag C partition and use CHKDSK command to check the partition, these steps can check out the potential errors which could affect you resize parition,.

And I don't know why you want to shrink a specific value, otherwize you could directly use Windows build-in disk management to rezise partition. if you are using windows7 choose an software Partition Magic for windows 7, here is the link: www.partition-magic-windows7.com