I currently use the Memory Map software with both OS and Aviation Maps and think it's great. I have it on an iPaq which (until I blew it up recently

) was great. With a seperate GPS receiver you can run the Memory Map software when you're walking, cycling, flying, sailing, green laning etc, then run up TomTom for the Pocket PC and you've got a true Sat Nav.
Using the Memory Map software on the PC you can even scan paper maps orientate them using known references and then upload them to your Sat Nav. I've not tried this yet, but may well try soon with the Michelin map of Morocco.
Memory Map is not a 'navigation' package. You can plan and record tracks and waypoints etc, but it does not tell you how to get from A to B. That's where the colaboration with Road Angel comes in.
The am contemplating updating to a
QTEK 9100. This would give me all the advantages of the iPaq (web browsing, email, Pocket Word, games, music) as well as the functionality of a mobile phone and WiFi.
I accept that (as proved by me blowing my iPaq up (I think I shorted the charging circuitry

)) these devices can be a bit fragile for use on a GS, however, the level of functionality they offer outstrips anything else on the market.
There are already ruggedized handhelds on the market, but I think this
Road Angel device will be an interesting halfway house.