Well, assuming McAfee isn't tied into the laptop's BIOS eeprom storage security or the hard drive's built in security:
If the laptop came with Vista or later then grab and image burn the corresponding Windows ISO image
on Digital River (assuming you don't already have a appropriate disk on your own). Use the product key found on the laptop's affixed certificate of authenticity
. Kill all partitions, repartition and quick format before OS install.
If it is XP then legally you will either have to use an alternate like Linux distribution, buy a new Windows OS license or find a OEM or retail XP copy that matches the laptop's product key license (i.e., Home with Home, Pro with Pro, MCE with MCE).
One other possibility would be if you can look up the manufacturer's instructions for performing a BIOS Menu Function key recovery install on their tech support page for the laptop. If this is available, not disabled and not password protected, then holding down a specific function key during boot will activate the restore OS to the way the laptop OS looked when it left the factory from the recovery partition on the HDD. Then you would need to install updates. EZPZ
If hard drive is password locked, then replace HDD with new one. Likely have to toss old drive but you can try rockbox crack. Unfortunately this can trigger the eeprom password lockdown if set and set to go off upon HDD removal. Several ifs. Hopefully their IT was lazy.
Hopefully the laptop was not reported stolen.