If you want to wipe the drives and you have a windows Xp CD.Boot off the CD and go to the screen that has what drive you can pick to install xp on and just delete all the partitions and then format one ntfs, if you don't want to install xp just reset the pc and put whatever os u want on there.
OR if u have another pc take the hard drive out and pigback it to another computer and wipe it.
OR if you already have a OS and you were going to dual boot windows7 then right click on my computer then click on manage then disk mangement and from there you can delete, repartition and format what you want that is ofcourse if you are using windows.......