Im not too sure... it could be (though I doubt) these monitors sync down to 15kHz so can display the likes of PAL and NTSC... but it doesnt state they do, and I doubt they do...
Those adaptors wont double the scanrate so you will only be able to use VGA screenmodes on a VGA monitor, which means no playing games on the monitor, you will still need a TV for that, workbench and other apps which can open on a specific screen will be okay though.
Hope that makes sense, its late and im full of flu so do excuse me.
