I wouldn't be able to get along without some kind of handheld calendar, address book and check/debit register. For confidentiality issues, you probably wouldn't want an Android phone (since it's all Google stuff), but a Blackberry is as secure as anything out there (including paper, that's too easily lost and can't be locked), and iPhones aren't far behind in terms of security.

I was fine for years with a separate PDA and regular phone, but it's so much handier and less bulky in my purse having a single device. It's true it's more bulky to run and ride with - situations where normally I'd carry only a phone, not the PDA - but I deal with that.

I'm old enough that the paper thing was my only choice for years. Spent way too much time manually entering everything in two or three different places and never being 100% sure whether something had been "synced up" or "backed up" or not. Never looked back.

I have my Garmin for navigation on the bike - but the phone is great in the car where I can plug it in, and I can't count the number of times that it's saved me from having to pull over and dig for a map that I might or might not even have.