Everyone on this forum of course abides fully with microsoft and all its licencing
I would go with a format although anyone who really still wants your data will be able to recover it.I doubt you have any national secrets on your pc so I would imagine your safe.
When ive resold ex business pc's ive always done more than a format.I take the hdd out in front of original owners,then place it on a hard surface and repeatedly whack it with a 2 lb lump hammer.By far the most secure method.To actually totally wipe clean a hard drive it needs to be exposed to magnetic forces beyond the availability to us lesser mortals
