As long as you format the hard-drive prior to doing the clean install of Windows using the Recovery disks that came with the computer-in-question, all should be well.
Note: If the computer came with a Norton or McAfee free-trial preinstalled, it'll be installed again - but invalid now. You MUST (a) uninstall the free-trialware AND THEN (b) download run the appropriate removal tool [1][2] & reboot (c) BEFORE you install or attempt to install any updates AND BEFORE you install an anti-virus application (e.g., Microsoft Security Essentials - free).
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