My B&W G3 came with a Macintosh video --> VGA adaptor. I don't know if these will work on PC's, but you might be able to hunt one down and try it.
Please note... If you buy that monitor and then you buy a G4, you won't be able to use it with the G4 without an adaptor. The monitor you mention uses the old proprietary Macintosh video connector, but all new G4's (and every Mac since the B&W G3) have a standard VGA connector.