Why is screen-size always measured in inches here. This 'huge' 5" Dell has the exact same resolution as the N900, so you should be able fit the same amount of web page on the screen anyway. Stuff will ofcourse be a fair bit smaller on the N900, and for some people that will mean more zooming on the N900, but even then this Dell won't get that much more content onto the larger screen.
It does make the battery run out faster though (more backlight) but it will probably also make the device a bit cheaper.

Anyway, you should all buy whatever you like, not what I like (unless your planning to send it to me )