Best tablet computer for mathematics I'm not sure if this is completely appropriate, but I thought I'd ask here.
I'm in the market for a tablet computer.  Unfortunately, my (mathematical) needs are very different from the needs of the sorts of people who usually review these things.  Namely, I want the tablet that is best for preparing lecture notes and taking notes in seminars.  It seems like most of the reviewers on "computer" websites are either looking for toys (like the iPad) or tools for creating art.  I just want the most efficient way to create a multi-page handwritten pdf.  Does anyone have any recommendations?
 A: I recently got an HP tm2 -- very affordable (compared to Thinkpads, Latitudes and motion computing slates), good specs, wacom digitizer+multitouch, 5h+ regular battery life. 
Productivity is great using Xournal  under linux (kubuntu, almost flawless hardware support). Xournal runs on windows, too, btw.
During a conference recently Xournal was brilliant -- infinite paper with infinite zoom, free rearranging, shape recognition etc. makes it easy to keep good notes (except that, well, it's still my handwriting...). The battery life of the tm2 lasted an entire conference day (with dimmed screen and wifi off).
You might want to check out the gottabemobile blog. It is an good source on mobile computing, with a lot of reviews on note taking software for tablet pcs and the iPad.
Generally speaking, pressure sensitive touch technology (like wacom or n-trig) gives better results for handwriting. But some iPad apps have features to compensate for that.
Being on a budget, a graphics tablet is a very good alternative for taking notes. I used to use one extensively before, especially for online whiteboards (like scriblink and dabbelboard) during phone conversations.
A: Just about any tablet PC ought to work for this.  I used a Thinkpad X61 Tablet for several years, and after it broke I bought a Thinkpad X200 Tablet.  A typical Windows tablet comes with software called "Windows Journal" which works well for taking notes, and can print to PDF using PDFCreator.  I also purchased a program called PDF Annotator, which lets me hand-write notes on top of any existing PDF file.
When I was first considering buying a tablet, I had trouble deciding between the slate type and the convertibles that come with a keyboard and a swivel screen.  I decided on a convertible, and I'm very glad that I made this decision -- my tablet also functions perfectly well as a standard laptop, and I keep it in laptop mode about 90% of the time.  A straight-up tablet with no keyboard would be almost as expensive, and would be considerably less useful.
A: To address part of your question, the iPad is far more than a toy for mathematicians, especially for reading mathematical articles.  Goodreader is the best means of reading and annotating PDFs I’ve ever seen; in particular, the usual size of LaTeX articles fits very well on the screen, with a little zooming, even in portrait mode.  I’ve virtually eliminated my use of my printer, both for reading others’ articles and correcting my own XeLaTeX output.  
Be very sure to test a PDF reader on real articles before it’s too late; even Adobe renders the Computer Modern font unacceptably on-screen, though with decidedly different results in different situations and platforms, and Okular on Linux is virtually unreadable at 100% zoom.
For note-taking, I’m not a big fan of raw handwritten text (disclaimer: I worked at Apple during the Newton days, and at Palm); I expected to have to buy a hardware keyboard for my iPad, but haven’t needed to yet.
A: Apple Tablet Custom Mods : There is a company which takes Apple laptops and custom modifies them into tablet computers.  You end up with a full OSX computer which is also a tablet computer, without the limitations of the iPad.
http://www.itablet.theplaceforitall.com/about.html
There are people who've also undertaken this modification on their own
http://www.fabiennemaurer.com/blogflo/?page_id=83
and you can probably buy an old 500-700 MHz iBook for less than 300$US and get it modified.
I agree with you that the iPad is not set up to be a serious tool and the need to type on a virtual keyboard makes it less useful than even the Palm or Graffiti software from almost 15 years ago.
If you really want to make a PDF of handwritten notes, likes the collection of Edsger Dijkstra's handwritten computer science notes at the University of Texas  (for example, http://www.cs.utexas.edu/users/EWD/ewd10xx/EWD1036.PDF ), the best way to do that is to actually hand-write your notes on paper and then scan them in at a later time.
A: Clifford Johnson has two nice posts about this (concerning the iPad) on his blog:
http://asymptotia.com/2010/08/27/my-office-in-my-handbag-the-ipad-as-a-serious-work-tool/
http://asymptotia.com/2010/08/31/a-letter-for-you/
A: A thinkpad running Linux and Denis Auroux's Xournal program works well for me.  Not cheap though...
