I am involved with a large on-line e-print project.  The
whole system of on-line research documents in science and
mathematics depends on Netscape helpers for DVI, Postscript,
and PDF.  Unfortunately the Red Hat distribution for
Netscape is not configured to include these helpers.  Life
would be a lot simpler if xdvi were the default
application/x-dvi helper and gv were the default
application/postscript and applicatoin/pdf helper.
It would be better for Netscape to look for these and not
find them than to not look for them at all.