I have the Vista HCx and love it. There is not much it doesn't do, or should I say it does EVERYTHING all those other units do and then some!(except talk)
It has an altimeter and electronic compass so you can swing a bearing standing still(moving less than 5mph) I would highly recommend a Garmin handheld that has at last a "H" and an "x" in it's name. The H denotes high sensitivity. I can sit inside a building(wood frame/shingle roof) and still get at least 3 sats. the "x" is for expamdable memory. I curently have a 2gig microSD card in mine loaded with City Naigator North America, National Parks East 1:24k (where I live is in those maps) and Blue Chart-Americas and still have well over a GIG of memory left to store waypoint, tracks, poi's and anything else that may trip my fancy. Most of the units that have fixed memory only have 24megs if memory serves me.
I payed $239 for my GPS which came with Mapsource for the computer and around $80 each for the three different map software I am running as well as about $50 for the 2gi micro SD card. It is not a $200 self contained unit bu it does a HECK of alot more