as a matter of interest, I have Win98II, and the schwa displays fine in both Opera and Mozilla browsers....but I don't understand where it is stored...I don't see it in either of the fonts I have as default, nor is it in the Symbols font, as some things are...
Where I DO find it is in a font called Grolier 2...here is a screen capture of part of that font, with the schwa at position 39. (lots of strange characters in it!)

It will be interesting to see what Mark comes up with as the key to the whole thing...that is, why I see it and Snuffy only sees it at work and why the fonts don't seem to make the difference..