Finally I went ahead and bought myself a tablet pc, my first laptop ever :) I ended up with a used Fujitsu Lifebook T4220 Tablet. I totally love it. It's sooo cool to finally be able to draw directly on the screen in Flipbook.
Even though it's a few years old, it runs Maya 2009 pretty good. I've played around with Bishop and it's no lag at all....even Bishop 2.0 works okay.