Drive Letters after eliminating Dual Boot

When I had a dual boot, my Windows XP was listed as the C drive. I installed a separate SATA hard drive with Vista and set the drive letter to V. I also have an additional SATA drive that I partioned into drive D and E for storage.

Now that I have eliminated the dual boot and have Vista as my only operating system, is there any way I can change the drive letter from V to C.

The drive C that I had Windows XP on can be changed to a different drive letter but I can't find a way to change Drive V to C as it is the drive that has the Vista Operating System installed.

Any ideas on how I could do this would sure be appreciated.