About the only thing I use my computer for is tracking time and distance for my logs. If I really want to know the average speed, it's pretty easy to calculate from those figures anyway. I use a very simple computer I bought at Target for $9.
After using my HRM for a couple of weeks, I learned exactly where my zones are. I know when I'm in or out of them. The only time I use the HRM is for recovery rides because of the tendency to work too hard.
Az