Generally you can expect an accuracy of
3 meters if WAAS is working
8 meters without WAAS
30 Meters under tree cover

Bear in mind that a 6 figure reference defines an area 100meters square, so the GPS is pretty accurate.

Garmin and magelan units are designed to be tough - drop your expensive PDA in a puddle and see how it fairs! In heavy rain the unit might be unusable wheras the Garmins/magelans will keep going.

Better to buy a cheap etrex and spend the rest on memory map, anqueet or fugawi for mapping points on to OS maps then download to GPS or print out as many times as you need.

Just MHO