I've ridden both with and without a computer, but I think people tend to romanticize the computerless way a little too much. My results for any given type of ride [easy/recovery, hard/fast, etc] tend to be the same regardless of if I am using a computer or not. The psychological effect of computer data ought to be completely under your control, but it can take some time to learn how to manage that and not let the numbers get to you.