I've been using an HP TC1100 as my primary computer for the last 8 months and love it. The form factor of the HP allows me to just carry the slate and pop it in to a dock when I'm working at me desk. The processor, a 1 ghz Pentuim M has plenty of throughput and all applications seem to work fine.
The slate fits nicely in an executive portfolio and the base unit provides about 4 hours of battery life. For those times when I need an extended battery I have an Electrovaya Power Pad which will give me a whole days worth of power. I like how the tablet can be undocked without turning it off allowing you to just grab it and go to a meeting when necessary.
When I'm travelling I always carry my keyboard with me but since it attaches or detaches in seconds it is very easy to switch between different tablet modes. The HP swivels similar to a convertable but also gives you all the benefits of a slate pc. While the screen is small, this is part of the smaller overall foot print and I'm willing to sacrifice screen real estate if it means I'll take that tablet with me pretty much every where I go.
I use an Aircard with the tablet giving me Internet access from pretty much anywhere. The tablet combined with Electrovaya and Aircard are a road warriors dream. Once you've used digital ink there is no going back from a note taking perspective. Hand write your notes and have them fully searchable.
The tablet is like a laptop on steroids. The only problem is that once you've had one you'll never live without another. My PDA is gathering dust as the tablet has become my primary tool. HP has a Quicklook Utility that gives your tablet limited instant on capabilities similar to a PDA.