using cmd you have access to everything your computer has, s/he can leave a door open for further entrance, there are lots of possibilities, and it doesnt take much time.
to be on the safe side, here is a install guide for windows 7
http://forum.notebookreview.com/wind...languages.html
and yes you can actually save your docs and your things, I dont think they will insert a virus on it, its a possibility and may make the process more streamlined, but wiping the drive should solve that.
Im very conscious of what I download or do in my pc, its simple I do like ron, passwords that arent problematic, like for this account I leave them saved, otherwise, like for my amazon account, my bank, or any other things that will have my info, I will not save. Aside that they all have very different passwords with numbers, letters and special characters mixed.
Its simple things, but doing this Im one of the few people on earth that doesnt get spam, and I know I will be safe. Aside that I always have my OS updated, my anti virus as well.
You dont need to freak out, you need to do what you need to do to get this fixed and follow simple rules afterwards, it may seen a lot, but I dont get any virus for at least 10 years, never had my credit card stolen, nor info. My security professor is much tighter than I, but what I do I think its enough, I dont need a super fancy physical firewall or some other things that he has on his personal server, clearly way above beyond duty