i used to use partition magic, but ive had no end of problems with it, and it doesnt work on vista.
i now use: EASEUS Partition Manager 2.0
its freeware, works on vista, and hasnt let me down yet
although i had some unallocated space on my drive. tryed to add it to my main operating system partition, but it gave me some sort of error. had to do it in my recovery os. give it a go though.