IE7 and Mathematical Characters

Certain mathematical characters no longer display in the default font of IE7 unless the operating system is Vista, including the "union" and "element of" characters. To get around this, in CSS you have to specify a different font, and the most common Windows font that works is 'Lucida Sans Unicode'.

Example:

∈

will display fine in both XP and Vista, but
∈
will not display correctly on XP.