I have an easy solution. Simply turn your computer on and format all the drives in your computer except the one caring the operating system. Of course, you should back your data up before doing it. And then put your windows installation disk into your computer and restart it. Then follow the instruction to setup a new windows but don't start the installation. When the installation asked you to show the drive direction, there will be some option to "format" and "delete" drives. You just format the remaining drive and then you are all set. If you (or the other person) want re-partition it, then just simply delete the drives and put them into a single unallocated memory.