The surface of mine is only 4x5, but moving the pen, it actually covers the entire monitor...I don't know what the surface size has to do with the canvas in front of me on the monitor...
When my friend first suggested I get one, I could only find them online and this size was over $300-others were from $600-$1,000!!!!
Now, Circuit City has them (it was funny, when I asked for one back then, I was directed to their cell phone/PDA department-the clueless bastards
), and they are very affordable.
What's really nice is that I am a lefty and until this, I was drawing with the mouse in my right hand. The spouse remarked it was kind of funny seeing me draw normal but still use the mouse too-double handed drawing
Edit for anyone looking for one: It was gotten at Circuit City....