CS5 Suite from old backup won't let me open programs on new Macbook, help please..

I had CS5 Creative Suite on my old macbook that was stolen around christmas. Now on my new Macbook after I go onto my external hard drive, where I have my old laptop backed up, and try installing the suite, none of the programs will open up, I keep getting an error? Any ideas? I don't have the disc anymore, it was taken too, but it tells me I need to uninstall and then reinstall. Any help would be great. Thanks!