[Groff] Umlaute

[zoon]

When I use groff on the win-xp platform, all german Umlaute like äöü
ÄÖÜ work fine (latin-1) - but when I work on the linux platform (Suse
8) the editors äöü become garbled. What would I need to do?
Change groff? Change system?
Thanks for any hints, Thomas