If you are on GNOME, you can always use GParted. From a clear and simple interface, this program will allow you to carry out all kinds of operations relating to partitions on your hard drive, such as resize them, create them, delete them, or change its file system.
It supports a large amount of file systems, such as ext2, ext3, fat16, fat32, hfs, jfs, linux-swap, ntfs, reiserfs, reiser4, ufs, and xfs.
Gparted is comparable to other famous programs such as Partition Magic, but with the benefit of being completely free.
All this makes GParted an almost indispensable utility on your GNU/Linux distribution.