If you are happy with running every game at 640x480 (your desktop resolution) then set your mame.ini for a fixed resolution monitor, this is done by using this option:
monitor lcd
Also, you need to use a monitor_specs line, where most of the values are dummy* ones and only the last ones are relevant:
monitor_specs0 29100.00-31500.00,50.00-65.00,1.200,1.200,3.000,0.028,0.044,0.524,0,0,480,480
Use the video interface that works best for you, when scaling is involved d3d is usually faster:
video d3d
That should allow you to run all games at your default desktop resolution and refresh.
If you want to play a little more you can install Powerstrip and once it's activated use this option:
powerstrip 1
That should allow an aditional tweak of your desktop resolution to approximate the game's native refresh keeping within the ranges specified by the monitor_specs line (*that's when the values at the beginning of the line are actually used so I chose some logical ones for a VGA monitor).
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At some point, consider using WinXP 64 instead of Win 7, it will make your CRT's life easier.