printing postscript

Folks -

Now that C-band Difax is dead, we actually have to start using our Unisys 
contract.  We have a Unix box and a good-quality laserprinter, and would like 
to convert the maps from pcx to postscript and print them out.  So far, we 
haven't found a graphics conversion package that works:

xv produces 72x72 resolution images which are of poor quality. Surface maps, for example, are unreadable. convert (ImageMagick) produces high-resolution, top-quality graphics.
The postscript files are actually smaller than the ones produced by xv.  But 
the files take 10-20 minutes each to print, while the xv files take only about 
a minute.  At that speed, we can't keep up with the maps.

the ppm conversion routines produce huge (several tens of megabytes) postscript 
files.  I haven't even tried printing one.

Am I doing something wrong, or missing the magic option?

Thanks in advance.
                                               - John