The Ultrasharp are crisper displays. WSXGA is higher resolution (and therefore smaller icon/pixel size) than WXGA.

Do you think it's worth the money?

And what resolutions can each use?

It depends on what you like. Notebook LCDs are designed for a single resolution - anything lower and the display will not be as clear.

For me XGA is the best. I've had the others and found the icons and text too small. I wound up changing the resolution thus reducing the clarity. For general text and web surfing I recommend xga. For graphics, design work, and advanced photo editing, the higher resolutions are probably better.