Steve, the touch screen you link to is exactly the one I purchased, but now that I have it, I realize I could have saved some money on one like this...
http://www.newegg.com/Product/Product.aspx?Item=N82E16824176356For the purpose of working using touch in Sonar, the extreme edges of the screen do not matter that much. There's a lot of stuff on the web about how you need the edges of the screen to work for swiping in from the right or down from the top, but I do very little of that in practice. I mostly launch and close programs with the keyboard or by using the quicklaunch at the bottom of the screen. I use the touch for controlling faders and pans and playing with synth settings or TH2 stuff. I use it when I'm practicing my guitar A LOT to zoom and rewind and play and change tempo.
When I'm getting down to business of mixing a big multi track project, I pretty much sit back and work my keyboard and mouse like I always have. Then, when my friends come over, we turn off read automation and play with the console view as we listen. Anyone can adjust anything they like to solo or listen with different settings to get a sense of how it would sound if we bumped this or that.
When I get another touch screen, I will get a two point touch screen that is significantly cheaper than the one you pointed out. Frankly, that would have been a fine entry point for me. I bought the other because I read about lots of 'compatibility issues' which frankly wouldn't effect me as a Sonar user.