How do you format a drive?

I've got an external drive from my old PC (PC is now dead) that is formatted as NTFS and I want to format the drive as HFS+ or whatever the Mac format is. However when I go into Disk Utility all the formatting options are grayed out for the drive and in the info it says the drive is not writeable.

Obviously I know that OSX can't write to NTFS in terms of files and folders but is there a way of just wiping the drive and formatting it for use on a Mac without having to find someone with a PC to let me do it?

Oops sussed it! I was being a bit premature in posting.

For future reference for anyone else that wants/needs to do this you need to delete the existing partition first!