The actual Pocket PC operating system comes with Pocket Excel, so no problem there.
Excel and Pocket Excel sync nicely, but only the more simple functions, ie no complex functions or automation (I have an iPAQ). However any sort of logbook, or budget/milage/expences etc is simple Excel functions. You could very easily duplcate your paper logbook into Excel and add some formulas at the bottom of columns to add things up. Easy enough to do yourself.
However, I bet you'll be re-inventing the wheel, this must have been done by many others?
Search on google for anything to do with excel logbook pocketpc etc and take your pick from the many.
The main problem for any paper-based person moving on to electronic forms... they don't back it up!
Let your iPAQ go flat (1-2 weeks no charge) and you lose your logbook.
What's the legal situation? (I'm an aviation newbie), do you need to print paper copies (for signitures?), or can you keep electonic docs only.
Hope this helps
Cheers