When viewing a 4:3 source, a 17" 16:9 monitor has roughly the same image size as a 14" 4:3 monitor and will show vertical black bars on either side of the source.
When viewing a 16:9 source, a 17" 4:3 monitor has roughly the same image size as a 15.4" 16:9 monitor and will show horizontal black bars on top and bottom of the source.
But a 15.4" 16:9 monitor, viewing 4:3 source, only has roughly the same image size as a 12.9" 4:3 monitor. Gettin' down there.
Just some thoughts...