lol, so it made you a basic user and doesn't allow you to install as you're not an admin anymore. Haven't seen one of those in a long time.
Don't know how bad it is but you should boot to the command prompt (that C:\> looking thingy). Try the format C: command. It might not work. If it doesn't, the easiest way to do this is get your hands on a windows 7 cd and boot up and reformat/reinstall from there. There are *cough* free ways to get windows 7 online. But you got to be ready to do some work. If you just want it fast and no headaches, get a cd and redo from there.

P.S. If the format command works and you have other partitions, destroy and recreate the partitions and reformat them too (fdisk is the command). The advanced virus' should have infected those areas too.