Touch screen Word Processor for note-taking

I'm looking to find some app or device that enables me to go from typing out notes to drawing graphs (freehand, or using a compatible pen) for my economics classes. Ideally I'd like it to be word compatible so I can open the document on my laptop as well as my tablet.

FWIW, I have a Macbook laptop and a IPad2 (which means with my existing equipment, my best hope is an ipad app). However, I'm no longer wedded to Macs; I'm considering buying one of those HP touchscreen laptops or something like it if I can get the benefit of being able to type and freehand notes in one document. Let me know if you have any suggestions, and thanks for the help.