ok.. i recently upgraded to powerbook 15" 1.5 with 512 ram. however, i am doing video editings alot. so, hence, i asked the question in digital video forum and heard that there wouldn't be much difference in using RT even if i do upgrade the ram... i was thinking about upgrading it to max at 2gb. but.. if i can't do RTs on my powerbook, what would be my advantage of upgrading the ram (video editing and all the other stuffs)? i feel like i am doing everything fine with 512 ram.. but.. i really want to know what i would notice significantly by upgrading the ram from 512 to 2 gb. i would know the advantage in video field, but would like to know other advantages as well.. thanks guys.. for looking at such intermediate questions.