Older Word versions don't natively support EPS and can only show the
bitmap preview included in the file.
The PostScript interpreter built into the newer Word versions only
offers partial support for Level 3 PostScript, and in general doesn't
receive too many kudos from what I hear and read.
I'm not sure what Word XP does when you send the EPS to a PostScript
printer - whether it uses the interpreted (GDI display) version, or
passes the EPS code straight through to the printer. Your comment that
it prints Ok might indicate the latter.
If you can't find a way to fix this, a solution might be to use our
ps2vector software as an intermediate step. It is a commercial
software tool to batch convert (E)PS to a number of vector graphics
file formats, including WMF and EMF for use in MS Word and other
Windows/Office applications. Vector graphics, raster images and font
text strings are all supported and preserved as such, and the software
offers full Level 3 PostScript support. ps2vector is most often used
for output from technical applications, such as designs, plots,
schematics etc. It has been around since 1995.
If interested, you're welcome to send me a sample EPS file from your
inhouse application for testing. I'll send you back the conversion
results along with further information.
Jeroen Dekker