After lots of trial and error I have Mamewah up and running on my Windows 7 Machine using an Ultimarc ArcadeVGA 5000.
When I previously used XP it reported the ArcadeVGA resolution of 640x480@30Hz Interlaced as 640x480@60hz. 640X480 Mamewah layouts worked perfectly with clear text even though the actual resolution was interlaced on a 15 KHz Monitor.
In Windows 7 Mamewah would not start until I changed to layout with the editor to 30Hz to match the Windows reported refresh rate. Mamewah works again, but now looks fuzzy with the text being far less clear. The actual resolution is exactly the same on the same monitor. I have contacted Andy at Ultimarc and we both think this is a Mamewah issue as everything else looks perfect I.e. desktop, emulators etc.