One of his friends gave him Netscape, and now he's using that, but he really wants to get back to IE. We tried uninstalling it, but it isn't on the uninstall menu anymore he says! We couldn't even access it through a DOS-prompt!
uninstall IE? Im not sure if thats possible, but you can make it so its not your default browser anymore-

Start >> Control Panel >> Add or Remove Programs >> Add/Remove Windows Components >> Untick the box next to Internet Explorer

If you cant uninstall Netscape, you can go to IE by going to start >> all programs(or program files) >> Windows update - browse through this IE window