The return of touchscreen?

Remember back in 2002, when Microsoft had these big plans for tablet PCs, with a whole separate version of XP?

Yeah, you probably don't, but back then I had this wonderful pipe dream for a slick note-taking application. First, it would obviously need to be able to open and write a variety of file formats, including plaintext, richtext, MS word, PDF, and PPT. Being able to annotate the last two formats would be especially wonderful for marking up papers and lecture slides. Couple this software with handwriting recognition, a computer-algebraic system, and graphing capabilities, and math nerds would eat it up. Imagine being able to note down equations, converting them into symbolic entities, manipulating and solving them in software. As a tool for doing math homework, it could be invaluable.

Separate pieces of software would probably be likely to simplify things, but if they were all made by the same company and shared UI structure...