I recently upgraded from Panther to Tiger, I backuped all my Apps from the application folder. But when I'm copying the apps back to my new Applications folder, the apps won't run, but when I download a fresh copy, the new app would run, the backuped ones won't.
Which apps in specific? It really depends. There are apps like MS office that you can just copy from one mac to another. And there are apps that upon installation, also puts a lot of hidden files in the system folder which it needs. Thats why it doesn't run. So I suggest you clean install again those apps that don't work. You should have used the upgrade installation of Tiger, that way everything would still be intact.
All of the apps that I've tried don't work, they are freeware and shareware stuffs. so some of them don't need installations, drag and drop lang from dmg.