As everyone notes, the N800 is not a PDA. It's actually a palmtop, Linux-based, tablet computer. That means you can have whatever you want, one way, or another, and while it will not replace any specialized device with purpose-driven hardware, and software interfaces, it will do the job of almost all of them, and then some.

The key, I think, is to change your way of thinking. Most cell phones have reasonable PDA functionality, so move the calendar, tasks and alarms over there. For writing, note taking and so on, use the N800. I'm finding Google to be a good transfer medium. I have software (MyPhoneExplorer) that syncs my phone to Google, and an Extension that syncs my Thundirbird mail client to Google, and Erminig on the N800 syncs the GPE calendar to Google. Use the Google sidebar on your PC, and it gets pretty integrated.

BTW - I miss my T5. It died, and they replaced it with a laptop under extended warranty. For on-the-fly note taking, and calendar maintenance, the Palm OS can't be beat. Although, I'm enjoying using a PocketMod for the quick notes.