If you want a normal wipe, then just buy a Windows 7 CD and re-install it by booting it. If you want a full clean system wipe, Download GParted(IT"S FREE) and burn it to a CD, then boot that up. Then, you can delete the entire volume in the partition and reformat it to NTFS Format(Windows uses NTFS), then install Windows 7 with the CD you bought. If you cannot use the partition you formatted, delete it on the Windows CD(There are options there) and reformat it directly from the CD.
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