When I used to work for my college's IT department, whenever we received a new PC the first thing that we would do would be to format it with a fresh, clean windows install (the OEM usually only provides you with a disk with all of the crapware on it in an image, so find a copy of straight windows from a friend if that is the case and use the license key on the side of your PC, which they are required to attach, when it prompts you to enter a license).
I build my own PCs, so I never run into this problem. I usually go the same route when a family member asks me to setup their new PC.