Honestly no idea on the screen. I have a Dell 24" screen (can't be bothered to look round the back for the model number

) But they do quite a few, and I know that one of the other 24" screens that they do, which is almost identical to mine in appearance, is actually not very good at all for games (while mine is absolutely fantastic), so you have to be really careful.
Read plenty of reviews before splashing out on a new screen, bigger doesn't always mean better.
Edit: I got bored and checked, my screen is a Dell Ultrasharp 2407WFP 24in Widescreen. By that reckoning
this screen should be the newer version of mine, although I wouldn't take that on faith.
Personally, I have 2 of the 24" Dell screens (same model), one at home and one at work. I love them, and couldn't fault them at all. Also, since I've been using them, I've come to the conclusion that anything larger would just be excessive, I almost have to turn my head to see the extremities of the screen (rather than just move my eyes) as it is. It's entirely up to you, but given the price difference, I'd be more than happy with buying another 24" any day.