Here is some hard earned pointers on GPS selection
1. The larger the unit/larger the antenna= better reception. The newer units with the 12 channel parallel receivers are MUCH better than the older multipath units. Magellan' s have slightly better reception than the Garmins.
2. Software maps from ALL the vendors are not that good and they are proprietary. Garmin/Mapsource-slightly better. Magellan/Mapsend- doesn' t have trails.
3. 8 MB + of memory if you want to download maps is recommended.
4. WAAS enabled are more accurate when the satellites are in view <3m. Get a model with this.

Some sites to check out.
http://gpsinformation.net/
www.gpsnuts.com/
www.pocketgps.co.uk
www.dbartlett.com/