Hi Reece,
there's a little prog in WinXP [called 'Zeichentabelle' in german; dunno the english name] that provides every german 'Umlaut' [and strange other signs] for every installed font. Maybe you haven't installed it yet.
For installation go to Control Panel\Software\[Add Windows Components] or similar. You will be asked for your WinXP Setup CD. When it is installed you'll find a shortcut in ProgramGroup/SystemPrograms? Maybe it's already there. Have a look to the pics:
the little prog [maybe you know it already]:
For installation:
Sorry for my poor english
Greetz,
SSB