Both PS and PDF are extremely portable.  PDF is a better format, but not
	because it's available on more platforms.
	
I'm sorry to have to tell you that PDF is not at all portable.
Just yesterday I fetched a PDF file from America.  It displayed
ok on the screen, but was garbled to the point of unreadability
on paper.  This *often* happens.  (One effect is that some printing
characters act like long-distance TABs.)  Oh yes, it's Adobe's
very own Acrobat Reader that generates garbled Postscript...