[XeTeX] get xetex to use best fonts

[Lon H Mitchell]

Peter and Ulrike: Thanks for your suggestions.  Apparently the external 
location feature disables the automatic selection of italic and bold 
(and perhaps other things like optical sizes?), but I think for an 
isolated (one-font) problem like mine that's a workable solution.

Ulrike:  I'm using MikTeX 2.8 and have no trouble using the type 1 
mnsymbol fonts with pdflatex and the minionpro package.  Also, on 
another computer where I have not installed the minionpro package, I 
don't encounter the same issue, so I would agree that MikTeX is not at 
fault, but rather the problem seems to be peculiar to having minionpro 
installed.  In following the installation instructions

http://tug.ctan.org/tex-archive/fonts/minionpro/README

could adding

Map MinionPro.map

or something else be causing the trouble?

Thanks,

Lon