Windows 7 include a built-in functionality in Disk Management to shrink and expand partitions. No more 3rd party utilities needed,To get to this utility, open up Control Panel, and type in partition into the search box.. you’ll immediately see the link show up......Go Here
You can use the built in disk management system in Windows, you just need to have the free space available on the disk to be able to expand the partition (contiguous space - as in empty space right next to the partition you want to expand). You couldn't expand it to space after another partition or onto another drive.