I've used the AWmap GPS with XM weather for several years on an Ipaq
5550 and it has never crashed during GPS operations. I think it's a
bargain right now, actually.

What is important to remember on the PDA applications is that they
have multiple uses - address book, appointment calendar, etc. When
you close one of these windows, the app continues running, unlike in
desktop Windows. So before firing up the unit in the airplane, be
sure to do a "soft reset" of the PDA to flush out memory. Crashes are
normally caused by excess memory utilization.

I also purchased 500mb additional memory on an SD card that I leave in
the PDA full time.