I'm thinking about picking up a high end external monitor (http://www.engadget.com/2009/04/08/viewsonic-debuts-24-inch-vg2427-1080p-lcd-monitor/) and was wondering if there are any limitations to my macbook's resolution?
The maximum output resolution of any plastic MacBook is 1920x1200 via the mini DVI port with the appropriate adapter.
x3100 MacBooks did it better but even the GMA950 ones could output the full 1920x1200 to an external display.
chundles is correct, 1920x1080 is the limit
wrong.
OP, to answer your question, and i am surprised that no one has yet...
your macbook with the x3100 integrated chip can handle resolutions up to 1920 x 1200
You can also extend your desktop real estate to support the macbook's 1200x800 and 1920x1200 simultaneously.