[REQUEST] backing up files

hey i am curently using windows xp and i downloaded 7 but i want to back up all my files onto a exernal hard drive so i can put them all back on once windows 7 is installed but i wan to know what files should i put on it just my files eg.pictures,videos etc .. or is it also programs like in c/

like every single thing? Or you pictures , music , and documents?

Install Windows 7 On your windows xp hard disk the install will move all your files to windows.old

Good luck