Most Latex installations generate files with bitmapped fonts by default. There are two easy ways to use Postscript fonts, creating smaller files that print more robustly and distill to better-looking pdf:
dvips -Ppdf -G0 -f FILE.dvi > FILE.psNote the option -G0 (that is zero, not the letter O). Without it your .ps file will have strange character substitutions! These options make dvips substitute postscript for bitmapped versions of the TeX Computer Modern fonts, including all the mathematical symbols.