De Altere as fontes padrão do Windows XP :
Use regedit and change the following two keys of "MS Shell Dlg 2" and "MS Dlg" to whatever font you want. Make certain that
C:\windows\fonts
already contains that font.
Aqui está um arquivo .reg que pode alterar as fontes padrão:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\FontSubstitutes]
"MS Shell Dlg 2"="Tahoma"
"MS Shell Dlg"="Microsoft Sans Serif"