you can go in your Dungeons and Dragons Online directory and edit the file UserPreferences.ini
In there you'll find the following lines :
Code:
[Display]
RefreshRate=Auto
AllowFakeFullScreen=True
Resolution=1920x1080
FullScreen=True
TripleBuffering=False
SyncToRefresh=True
AllowWindowResizing=True
Antialiasing=8x
ConfineFullScreenMouseCursor=True
WindowedResolution=1280x1024
AllowDesktopCompositing=False
ForceFakeFullScreen=False
ShowIntroMovie=False
[International]
UseIME=False
[Troubleshooting]
EngineSpeed=VeryHigh
MaximumFrameRate=121
the one you want to set up is the Resolution parameter.
I haven't tinkered with it since ages, but I had to set up the screen resolution of a laptop that way.... 4 years ago...