I use 1200 x 800, the max for this Toshiba laptop 15" screen. I am also using a 64 bit OS and Firefox/Chrome.
Full screen in Firefox is a bit buggy but the way you get there if F11 doesn't work is right click on the toolbar icon for the browser. Hit restore and then F11. Works every time. Right click on the tool bar and uncheck Show Toolbars if you want to git rid of them too or you can auto-hide the toolbar in your Toolbar Settings.
There are no issues with Chrome and I suggest you give it a try. Doesn't mess anything up, is free and one click install without restart. GL.