1680*1050 isn't that much higher. It's a lot fewer pixels than 1600*1200.
1280*1024 = 1,310,720 pixels
1680*1050 = 1,764,000
1600*1200 = 1,920,000
1920*1200 = 2,304,000
That means a 20" WS is < 35% more pixels than a 19" 5*4.
In other words, if your videocard can handle 19", I...