I'm now running pocket george - and first impressions are good.
I bought a 2nd hand palm m130 on eBay for just over a fiver, downloaded the desktop & hot sync software on the web for free. It's a bit of a brick, but came with a leather case so should stand up to being knocked about in the van.
Easy to update jobs and payments as you go, and 2 minutes on the pc at home and everythings updated.
Highly recommend it.
Dave