maximizer sets the size of the window. if you also want to change the resolution of WoW itself you can manually edit the config.wtf file in your wow directory. So set the dimension for the window in maximizer to what you want wow to be and see if that works. If it doesnt then change both maximzer and the config.wtf to the resolution you want and try again. Keep in mind if you specify non-standard resolutions using either method the moment you go into video settings and hit the 'ok' or 'apply' button it will jack it up.