If the mount swivels, the monitor's designed for it (e.g. my work one - somehow I snagged the only swivelling monitor in the whole office). Failing that, it can often be remounted vertically with minor screwdriver attention (e.g. my monitors at my previous job). Weight really isn't that much of an issue with LCDs, particulary compared to CRTs. (Have you ever slung two 19" Sun monitors (34kg each) about, repeatedly as part of your job? Me neither, we had Windows admins for that sort of thing. Never go into Unix admin without a dodgy back.)