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#41
It is always best to wipe the HD of possibly conflicting or infected code. Formatting doesn't erase anything just clears the partition table. You want to be thorough, right?
It has the page file on it which is blocking formatting. Wipe it to get the cleanest slate and to recreate the Page File on the System Partition.
You should be able to run DISKPART Clean All command from elevated Win7 command line as shown in tutorial. If not, boot the Win7 DVD, press Shift F10 at first screen to open Command Line.