With the old EzMath you can generate code that you can paste in your webpages, even in the form of MathML
http://www.w3.org/People/Raggett/EzMath/
Now I am confused: when to use EZmath, when your TEx filter?
MathML is cumbersome to handle and doesn't "just work" when pasted into Moodle pages (for now) so if you need maths in Moodle now, use the TeX filter.
For the nonMathML option EzMath requires people to install a plugin (Windows only) on their computers, if they want to view the pages. Moreover such pages can't be printed. Even the MathML option requires IE users to install a plugin. And as Martin explained, MathML will not display in Moodle pages under Mozilla, because Moodle currently does not produce xhtml compliant pages. Finally EzMath can only display a rather limited set of mathematical expressions.
OK, enough I know what to choose when 