Is Ram more important than processing power?


Hi all adobe users,
quick question?
I edit on a 2.8 p4 with 256 Ram, i can't see the view screen as i edit my footage, only in slow moving jumping frames,
now my 1.8 p4 computer has 516 Ram but ofcourse the slower processer but it still runs much better.
Everything else between the 2 computers are the same so the conclusion i have come too, is that it's more important to have more Ram than it is to have a faster processor.
Is this correct or is their another reason?
Thanks for any replies!