Hi,
I'm sure the monitor will work, but either the 640x400 screen modes will end up using only the center of the LCD about 6" x 4" or the monitor will do an "expand" to make the lo-res image fill the entire screen - when doing that it will get a bit fuzzy. From my experience you may also have to adjust the little "fine adjustment" knob (thingy beside the de-interlace switch next to the video out port on the A3000) in order to eliminate the screen jitters.
Regardless, it will work and I'm sure you'll like the display.
-G