I was worried about losing “Tasks” too. Turns out they’re built into iCal! So no worries there.
Re: Notes, it’s a little more complicated. Anil Bawa says he decided to use Apple’s Stickies — like virtual postit notes — but I have a feeling I can do better. I’m thinking about using TiddlyWiki, a mini-wiki that has many devoted users and which I figure could be used on the Treo too, and with a little work, kept in sync. What I’m really going is something like the PersonalBrain software that Jerry Michalski told me about; it’s kind of like a wiki-mindmapping hybrid. But (argh!) it’s Windows only. Lucid Fried Eggs purports to be an open source effort to give a Brain to the rest of us, but I’m not sure it’s under active development anymore.
What I really want is something like a wiki — something that has a database backend and a mindmap-style GUI front end, with unlimited tags/keywords that can attach to every item so that you can navigate keyword-to-keyword, and with (of course!) outbound RSS feeds for each tag as well as for the whole enchilada. So, kind of a little more than Entourage’s built-in notes feature. It just seems stupid to use Word to take notes, when these flat-text files just keep my thoughts locked away and make them hard to find.
The other tool that Boris Mann points me to is OD4Contact. Since Boris’ offhand post re: buying an unlocked Treo is what tipped me over the Treo-purchase abyss, I’m inclined to follow-up on any tool that he tells me actually will make my life easier. I’m downloading it now — report to follow.