Shown here is gparted, the Gnome Partition Editor, which is one of the most useful programs I have. It's so useful, in fact, that I also have it on a stand-alone disk that boots a minimal Linux plus gparted. It's a GUI based disk partition manager, just like the $63 Partition Magic for Windows, but of course it's absolutely free. What I'm doing here is formatting my new 250 GB external HD to a Linux ext3 filesystem rather than the Windows-compatible one it came with. The ext3 filesystem uses journaling which logs intended changes before committing them to disk. That way if the system crashes (from a power interruption for example), it can recover by simply reading the journal.
Back when I was still using Windows, I used gparted to shrink the NTFS filesystem and make room for a Linux main partition and swap partition so I could run a dual-boot setup. Today I use it to carve out new Linux partitions for installing this or that distro to see if I like them. More often than not I don't like them, for a variety of reasons. They either flake out on me, or don't have the variety of software I need. So these days I mainly run my Hacky Linux, with Linux Mint waiting on the hard drive if I don't use the Hacky boot disk.