You can get an external antenna for the GPS unit I have, so just throw it into the glovebox and connect it to a power supply and forget about it. Personally I move it around as I may be using it in a different car or even occasionally on the bike in case I get lost on a tour (only after stopping of course) - haven't needed it yet but you never know.
I don't get on with Windows Mobile at all, and that's not an anti-Microsoft thing I just think its only saving grace is leveraging the Windows desktop. My dad's PDA is WM and I'm surprised the hard reset button still works it's been used so many times after lock-ups. Likewise a colleage had a WM phone (an SPV funnily enough, don't know what model though) and it locked regularly and took ages to reboot.
I use the iPaq on my bike (via Autocom), and it is also the MP3 player, with a Nokia being the phone. Bike to Bike comms via Icom PMR...
Anyone looking for Bike communications, Autocom is the way to go, and its possible to have conversations at silly speeds (obviously not recommended!), and the other party isn't aware you are on a bike...
As to WM, you mean soft reset
. Hard reset is back to factory defaults. WM is a bit like Windows 9x - any app can crash another. The key is to only install the apps you need, not chuck everything you can download to it. Mine (both the iPaq and the SPV) are stable - though occasionally resets when TomTom quits. Only apps I run on them are TomTom 6, Checkpoint (for cameras), Memory Map (for OS maps for when I go for a stroll), a couple of games, and the built in apps. I have had the SPV crash once on me in a call - but if you saw the state of the phone (it really has been knocked about), that is not bad.