When choosing a monitor, as any good cabinet building site will tell you there are 3 choices:

1) A PC monitor - limited in size, expensive
2) A TV - cheap, quite fuzzy compared to the others, more screen for your dollar
3) A genuine arcade monitor - can be nice and big (up to 27"), expensive!

As budget was important to me, a genuine arcade monitor was out of the question. However I was lucky enough to get a hold of an old MAGView 21" PC monitor that was heading for the junk pile. The monitor wasn't the sharpest thing in the world, and onyl managed a top resolution of 1024x768 at 60Hz. In it's day (Manufacturerd in 1983!!!) it was the bees knees, but today it was scrap.

MAME games are all quite low resolution, and typically around 60FPS/Hz. As such the monitor was perfect for what I needed.

After much fiddling with AdvanceMAME and custom modes, I gave in and settled on 1024x768 hardware stretch using the D3D blitter included with MAME, and bilinear filtering turned off. This meant no image blurring in games, and also that my monitor wasn't changing modes every new game (possibly extending the life of it a little).