The system partition (system reserved) on W7/W8 will be recreated if missing when performing the install. The W7 partition is 100MB, W8 is 350MB. Personally I would delete it and let it be recreated.
Just what I wanted to know, thanks. When I get the hidden OS key out of the BIOS I'll be all set to go on a clean install. When. So far three weeks of calling MS and Asus and still no key.