To use Mathematica with X-Win 32 you 
need to install the font files with .pcf
extensions on your PC locally. That's 
where X-Win expects to find them.

The fonts might be on the CD-ROM of your
Mathematica distribution or you can download
them from Wolfram's website

When the files are residing on your PC hard drive
let X-Win 32 know where to look :

1) Right click on the X-Win 32 icon on the toolbar

2) Select X-Util

3) Under `Fonts' select `Modify FontPath'

4) Enter the location of the fonts so that it appears
   as one of the font paths.