Unless you're unhappy with the U2410, I would say no. The viewing area and resolution is larger on the U2410. Save your money and get another for Christmas if you want to go dual monitor.
I decided to keep my U2410 AND one U2211H for now. The U2410 is my primary monitor and the U2211H is to the right of the U2410. I keep my email accounts, IM and sidebar gadgets open on the U2211H.
I'm very happy with the U2211H (replaced a G2410). The colors are much closer to the U2410's.