Mathematics tools

Hi Andy,
I really don't know anything about installing moodle filters. But if your old version of mimetex installed and ran, then the current version should do likewise. Note that your \underbrace problem was first mentioned in http://moodle.org/mod/forum/discuss.php?d=30166&parent=141570 by another moodle user. As you can see, he had no problems installing the same fix I gave you. If you've come across some new moodle installation problem, then somebody else (who actually knows about these problems) will have to help. Or, if jsmath is working for you, I'm sure you'll be happy with that, too.
John