Ipod Touch Applications?

do i have to have the lastest software (3.0) in order to put apps on my ipod? they are downloading to my itunes but wont transfer to the ipod itself when i sync it. the guy i bought it from had 2 apps on it and they wont go to my apps page. it says that my computer is not authorized to play them. so maybe he had the software and i dont so it wont work?