I always thought it was stepping away from computers in general that did the trick, but e-mail to myself and private journal entries seem effective as any pad of paper I've ever carried, while having the "cut-and-paste" advantage of instant usability.
So, next question.. Where does the magic lie? If it's the complete separation from all my distracting tools and toys, an office computer might facilitate that. If it's in the change of scenery, I should make obtaining a laptop my highest priority and make a point to move around a lot. But if, as I suspect, familiarity with the machine itself is what kills me, there's no practical way to facilitate constant change.
Of course, there's always pads of paper.