Replying to Calling on a really really good computer nerd

Hi, i recentely reinstalled windows xp on this computer. After finishing the installation i looked at the hard drive and realized my bros program files still existed under my program files. How do i get it so that those program files translate into real programs and work on my computer without having to reinstall everything? I tried clicking on shortcuts and .exe
s but it didnt work. It said you must instal blah blah.