Doesn't Windows XP SP2 have a Bluetooth stack built in? It's in RC1 at the moment, and I use it on my tablet and it's stable.
BTW, James, have you tried the "Create your own font" tool for the tablet PC? It makes a font from your handwriting... I'm using it in Windows. It's quite weird actually, but a cool concept
It won $15000 from Microsoft, so they obviously liked it!