I was going to go with the U2410 as at least it's brand new, but I hear only amazing things about the 2490.
Because people usually do not post "God, I was so stupid to buy a refurb for the price of a new one with worse exchange policy as well and as a result now I have to live with this giant dead pixel..."
I'm writing this on my shiny new U2410 and I have to say it's a very nice monitor. I have yet to get a W7-compatible calibrator and it's a bit on the short side for my taste when it comes to the highest position for the screen but otherwise it's a very impressive piece of engineering.