I can offer you a few suggestions on TPCs (tablet PC) and writing.
It is a fantastic piece of hardware for writers. Revolutionary in fact.
All your notes can be kept in one place (backup everything though!). I recommend OneNote. OneNote allows you to store all of your research (i.e. internet based) in one place and categorize your notes/research. If you're writing fiction keep your chapter notes, character development, storyline, etc in seperate folders. Then when you're ready to write, (if you have a convertable), simply flip that screen upright, place your hands on the keyboard and jam!
You never run out of paper, space or ink! You always have everything you need to work. So, the TPC liberates you. Go to the coffee shop, airport, hotel, beach etc and never even worry about leaving even a sticky note behind. (Yes, TPCs have sticky notes too!)
Now all that said I want to caution against some of the advice I've read above. First of all I would NOT purchase a slate. Get a convertable TPC. Converting handwriting to text will sllllloooooowwwww you down! It stifles your creativity and turns your right brain left. There is no faster input than the keyboard. When you are in creative mode you need to pump it OUT! The last thing you want to do is focus your creativity on why the OS recognized your "i" as an "l". You need a keyboard!
The handwriting input offered by the TPC hardware platform is best for keeping notes - YOUR NOTES. Don't convert them to text. If you are the only one reading them, then why bother? On the rare occassion you have to share your notes, type them. Or write them neatly and convert them to PDF.
Yes Vista recognizes your handwriting better because of the training, but honestly most folks who store their notes on a TPC, and in particular writers, do not convert the notes to text. So don't feel like you have to go Vista if you're not ready for that OS.
Final thoughts... I absolutley love the TPC. I am forever sold on the platform. I love Macs and will not completely switch over to the Mac OS because the TPC is so awesome for writing.
A good business foundation to build upon - Say what you mean, mean what you say.