Thanks for the info. Do you like your DELL latitude E6500? I am leaning towards dell because I have never had any problems with them and like the 3 year warranty it comes with. I have used a Dell Lattitude D810 for about 5 years now and it was a rock.
Not sure how the E6500 and the M6500 differ, but the M6500 I just got exceeds my expectations. Also, calling them to help me configure it saved me about 25% of what I was about to spend and got me better monitors than available via the configurator. If you want the contact information of the guy who helped me, PM me.
E6500 maxs out at 2GB memory when M6500 goes from 8MB - 32MB obviously they are not even in the same class. I would go with model that can take more memory. My experience with E6500 is unevenful nothing to complain about.
this looks pretty useful: http://www.engadget.com/2011/01/04/mmts-displaylink-equipped-15-4-inch-usb-monitor2go-given-a-279/
When traveling, I use my wife's iPAD as a second screen. There is an inexpensive app for the iPAD to make it happen wirelessly.