The Garmin 305 I mentioned interfaces beautifully with SportTracks.

You get full mapping, paces, even power if you have a Powermeter.

Download the "elevation correction" plugin, and you'll also get great, repeatable elevation data for your GPS-mapped routes.

The 305+Sportracks for me gives nearly everything I can ask for detailed training info. With the speed/cadence sensor, it makes my otherwise boring trainer rides very interesting, as I get very reproducible data on my fitness level based on speed/HR.