Perhaps not as fast as you do, but I'm going the other way, started with a macbook, cheapest version, found it had not enough real estate, bought a mini and a cheap 17" screen to go with the MB, found out it wasn't handy to have two computers, upgrade to a Macbook Pro 15" but when my wife's Toshiba died last week I went with an EOL MBP 17 Hi-Res.
This all took place in the last three years, so although I'm on a steep investment here, I'm probably not as bad as you are!
BTW, if you have a Hi-Res MBP, why on earth switch to a 23" ACD that has the same amount of pixels, but just a whole lot less dpi? Just drag the MBP a bit closer (or get glasses

) when you can't read it.
I just tossed out the 17" cheap ass screen as I didn't use it in over a week! Now my desk is a whole lot cleaner, have more space for papers, sheets, books and other stuff I work with.