I just got a Garmin Edge 305
. It's a bike computer with built in GPS. it doesn't have maps, so you can't see what street you're on, but it does draw a line. The best thing is when you get home, you can plug it into the computer, and it will show the whole route on a map, plus altitude, speed, heart rate, cadence, etc.... Plus you can see where on the course it happened. "I hit max heart rate of ??? at the top of that hill after climbing ??? feet over ?? miles." The 305 can record every piece of data, every second for 3 1/2 hours. or it will do a smart record for longer rides, and they say the rechargeable battery will last 12 hours.
Plus you can set up the display on the unit how you want, so you can see gradient, and altitude as your ride.
I got the 305, with the wireless cadence/speed sensor and heart rate monitor for about $250. You can also get without the extra sensors for cheaper.
There is also the 205 which doesn't support the sensors, and doesn't have an altimeter (just uses GPS,the 305 has a barometric alt. which is supposed to be more accurate)
You can just mount it to the handle bars turn it on and go, no hooking anything up. as long as it sees the sky, you're good to go.
They also have a couple of other models with color screens and maps, but they're in the $400-500 range.
I'm on a Mac and the software that comes with it is ok, but I've discovered Ascent
which is pretty cool. With that, you can select part of the course, and all the numbers are there.
Plus all of the software can do totals, so you can see on your calendar how many miles per week/month you do.