By get back the space....do you mean to just reuse the partition that ubuntu was installed on or remove the partition and expand the vista partition?

If you are trying to remove the ubantu partition and expand the vista partition then I would suggest that you back up the personal files and data and then just use the vista installation to reformat and resize the partitions...then reinstall the operating system.

Shrinking a partition and creating another partition in the unallocated space is one thing....removing and expanding is something different. I have seen many failures in expanding the partitions