In a way it's kind of unbelievable that rockers AC/DC have only topped the U.S. album charts twice, once with 1981's "For Those About to Rock, We Salute You" and 2008's "Black Ice." The same could be said of the band over in the U.K. -- up until this week.

The soundtrack to "Iron Man 2," essentially a hits (and misses) compilation of AC/DC songs from a span of 10 albums, has beaten out Paul Weller to No. 1 on the tally overseas.

But here, it's only estimated that the set will reach as high as No. 3 on The Billboard 200. Why the descrepancy?

Well, the U.K. doesn't have the newest "Glee" companion record, "The Power of Madonna" (yet). And Lady Antebellum is set to make a comeback to the tippity top echelon after the ACM Awards.

But it's also a bit of buying habits of the folks in the U.K. compared to us. Look at the recent No. 1s in this country: Justin Bieber. Usher. Lady Antebellum. Sade. Lady A. Ludacris. While rock 'n' roll is still a cherished and protected part of our music eco-system, it isn't as pronounced as the British buyers. Same could be said of dance artists, there versus here.

But seeing as "Iron Man 2" is a hot topic right now, it doesn't hurt that the album cover for an AC/DC set is nothing but a movie poster cropped down to CD jewel case size. So they've got that going for them.

The cross of movies and music isn't isolated to just this flick, either: AC/DC frontman Brian Johnson is contributing songs to a forthcoming film "Doonby," which itself has a musical bent. John Schneider has been tapped to play a singing bartender, in a plot that's described as "Crazy Heart" and "What a Wonderful Life" (as opposed to "Crazy Heart" with a girl).

After five years as a columnist and editor at Billboard, Katie Hasty joined HitFix in 2009 for music and film reporting out of New York. The Midwest native has worked as a writer, music promoter and in A&R since 1999 and performs with her band Numbers And Letters.