Since most of my clients are MS XP/Office environments, I currently have a Dell D600 that I truly despise. Reliable it is (now), but the BIOS had me reimaging the thing for a solid week before Dell was finally convinced that they needed to fix it. *Geeze- two years later and I am still irritated!*
I will be purchasing a new laptop in the next few months. Having considered all of the options, my choice is going to be one of the new Mac PowerBooks running OS X. From there, I will create a partition that will- with the help of Boot Camp- run XP.
In this way, I can use the computer for business and keep the XP partition for that purpose, as well as use the OS X partition for personal use- I LIKE command line Unix.
I use an iPAQ for organisational needs and found a great wheeled computer case at the local Wal-Mart. I don't worry about computer size as I don't carry it on my shoulder.
For note taking, I pull out the iPAQ and use mobile Word that I can synch with my computer later. I have been using Transcriber as I can quickly write on the face of the iPAQ and the iPAQ will transform it to print. I find that I can take notes as quickly with this method as I do with a pad and I have my notes electronic and publishable.
This is the soultion that I think is best for me. I don't care for tablet pcs as I can do the same job with a smaller tool (the iPAQ).
Good luck with your choice. I know you will find the right thing!