Two of March's most high-profile albums, U2's No Line on the Horizon and Kelly Clarkson's All I Ever Wanted, have already dropped off of Billboard's top 10, suggesting that neither one may have much staying power.

Released with great fanfare (and in the case of U2's album, a five-night stint on David Letterman) on March 3 and March 10, U2 and Clarkson both debuted at No. 1, with 484,000 copies and 255,000 copies sold in their first weeks. But they've since sunk like a couple of stones, each selling less than 42,000 copies this week. In fact, last week, Clarkson's album was in fifth place with 52,000 copies and U2's latest sold 51,000 to land at No. 6.

There were a lot of new releases last week (Keith Urban, Prince, Diana Krall, hip-hop act UGK, and former digital downloads champion Flo Rida), which probably took some of the sales attention away from Clarkson and U2, but there are plenty of other albums in this week's top 10, including the Twilight soundtrack, no doubt getting a boost from the film's DVD sales; Lady GaGa's The Fame and Taylor Swift's Fearless—all of which are older, and still more popular, than U2 and Kelly Clarkson.