Of those two I'd get the latter (Asus VE228H) because it's a LED backlight model. Although I wouldn't buy a screen unless I had read a decent review or two of it and then checked customer feedback/forum posts complaining about any possible problems.

Other than that, I'd personally get a bigger screen. In my opinion 23.5-24" is the way to go these days. They don't cost that much more anymore.