I've got a 14" monitor, everything works fine, nothing is massive looks like any other computer screen, only page I've come across that is massively wide is JJR's site, but I have a dual wheel mouse so no real issue. hasn't been a problem one bit
edit: 15 inch is the other one, this one is 14" measured diagonally according to the sticker on it.
If you adjust the frame size, can you see it? I've tested the page at 640x480, 800x600, and 1024x768 and they can all see the menu. I don't know why it wouldn't work at a higher resolution, the frame is a specified height, so everything should fit inside it nicely. ?(