use paint,
i know it sounds off, but i know the way you kids think (i was onyl at school 3 years ago and now im a network admin) but if you click open on paint and type c: and hit enter, you should be able to see your c partition. I dont know what you want to do with it, but cmd is in system 32 i think, or it might be system. either way, you can launch your command prompt from there and start nmapping all you want.
Just dont get caught. If your admins are anything like me then you will have hell to pay.
What im saying is, make shure your admin is not a BOFH,