your going to need a new copy of windows and a new key.
I am assuming your friend has an OLD version (pre-SP2) and his is probably bootlegged also. So no activation is required.
Windows update does a activation check now so if you aren't legit you cannot update.
You are going to need a new key and to reinstall with that key. If you are getting a new key just get the new copy of windows with it.
If you boot offa the CD you have a choice to install another version or overwrite the old version or clean format and reinstall(i.e. delete partition and reinstall). If you dont have any of the updates I would clean install anyway and do all the updates first before the programs because installying a ton of updates now will prolly jack up your system and bog it down or make some programs unstable.
I have had this same problem and have looked for hacked servicepacks and updates that I could possibly install but to no avail. This was for my g/f's brothers computer. He had to buy a new copy in the end.
If you just want javascript then just download firefox or some other browser.