I'm a newbie too, but DH who'd been cycling a bit longer than me, just bought my bike with a computer, so I've always had one too.

Mine has cadence, which I always use, because from what I've read, you should cycle at around 75-90 rpm. If you spin too slowly, it puts pressure on your knees. Although I also understand it's a bit of a personal thing too. I've read that Lance Armstrong is a bit of a spinner, and Jan Ulrich is a bit of a masher (goes the big gears).

Like all the others, I use speed, ave speed, distance and also time ridden. All this is really important for training, because you need to know that you're improving! For example, when I first started, I couldn't get past 20kph, around the neighbourhood circuit. But at my last ride, I averaged 24.4 kph. And as I ride a hybrid, I reckon that's not too bad although like everyone else I want to go quicker!

It's all useful info and money incredibly well spent. And I think it brings a big dimension to your riding.