I have a hard drive that I have partition into two drives, one with Windows Vista and the other with Windows XP. Now I want to make a third so that I can add Windows 7, but I have to allocate some space from both the Vista and the XP drive. So now I have two empty partition and want to merge the empty partition into one. How do I do this? If you mention some software, I would prefer it to be free software if possible. Thank you.