IMHO, about 500 nits (brightness) is a good number, get that if you can. Also, 600:1 contrast, and 9ms is okay for screen refresh.
Widescreen is a joke if you don't known what you're doing. Just for example, 19" 4:3 is a bigger screen than 19" widescreen (16:10 or thereabouts), so don't fall for that.
15" 4:3, 17 and 19" 5:4's ;)