I've tried for ages through the registry and got nowhere. I can change the resolution to really weird values with JazzRes but that still can't set it higher than 640x480 (although it helped me make my window just big enough to see the chat but unsquashed so I can position it at the top of my screen and do other things while I chat =)).. If anyone has any information on running JJ2 at a higher resolution please contact me, I've been trying for ages!