While there are now quite a few ways to skin this cat I noticed that there is no mention in Moodle forums of Eq2Img, a windows dll solution for a windows problem: http://www.codeproject.com/KB/dotnet/Eq2Img.aspx
It is certainly a simple solution for those running asciimathml on windows and want quick and easy mimetex fallback (though as noted elsewhere, falling back to the google chart api may be as promising a route.)
Please don't give me grief about bringing this forward and don't ask me for help with it - lol - though I have played with it on a <shudder>windows box</shudder> and it is pretty straight forward for windows. I am not a proponent of MS Windows or of Moodle on MS-Windows. I am not looking to make code more complex or starting a separate windows code project. I am only pointing out that for those who are so lost that they are bound and determined to try and make a silk purse out of a sow's ear that this might be appropriate for one of the two typical options (emulating *ix under windows or reconstituting as MS app.) Voilà! Une oreille de truie!
[NB No reflection on the author of the above referenced code or his code, which work very nicely despite the fact they are intended to work under windows.....]