My PowerBook G4 burns dvds very slow

hey my friend gave me a cd with a kill bill 2 in it , and i wanted to burn that to a dvd so i can watch it with my friends and im very new to Macs and i added it in Imovie and then i made the menu for it to start and started to burn on DVD+RW that i have and then its started to encoding frame by frame, after 1 and a half hour its not done to half the movie and its going so slow, im realye unhappy for the superdrive, then normal burning on DVD+RW for normal files goes very well but not DVD movies, im confused and Toats 6 i think its the same thing, I mean I got a 4.7 GB DVD-RW i insert in and I add a 600mb movie, toats it says its using 4.8 and u inserted a dvd with a 4.4 and the cd is new why did it tell me its 4.4 crazy :te:
Help Please !