Hair, it's not quite as drastic as it sounds, not if you've got everything backed up. I format computers at home all the time when the boys have drastically screwed them up. If you've got everything you need it's basically a piece of cake - unless you've got machinery that's too old.
Reformatting is not a big deal for a computer geek, but unless ksen is one of those (and I am not), I would be VERY hesitant tell him to reformat... in case something goes very wrong and he is left with a Boat Anchor for a computer.
More RAM is needed, but some improvement may be made by cleaning up and running leaner.