Landing the #1 spot at the box office in your opening weekend is easy -- just stick out your thumb, hitch a ride and hang on tight.

"The Hitchhiker's Guide to the Galaxy" rode to the #1 spot with more than $21.7 million, according to early estimates. The film adaptation of Douglas Adams' book of the same name follows Arthur Dent (Martin Freeman), a man who finds out in the span of one day that his best friend (Mos Def) is an alien visiting Earth to do research for the best-selling book "The Hitchhiker's Guide to the Galaxy" -- and that the planet is about to be destroyed to make way for a hyperspace highway (see "Don't Panic: Your Guide To The 'Hitchhiker's' Phenomenon And Film.").

"The Interpreter," which debuted at #1 last week, dropped down to #2. The thriller stars Nicole Kidman as African-born U.N. interpreter Silvia Broome, who overhears a plot to assassinate an African head of state. Sean Penn plays an FBI agent assigned to protect Broome, who is also a target. "The Interpreter" earned more than $14.2 million in its second week in theaters.

This week's only other new release, "XXX: State of the Union," bowed at #3, pulling in $13.7 million. While the last "XXX" film featured Vin Diesel in the title role, the Ice Cube-led sequel centers on Darius Stone (Cube), the new XXX handpicked by Agent Augustus Gibbons (Samuel L. Jackson) to foil a plan to General George Octavius Deckert's (Willem Dafoe) plan to overthrow the government. (Watch the first 10 minutes of the film as well as exclusive clips of Ice Cube discussing his career in "Ice Cube: Renaissance G.")

"The Amityville Horror" continued to horrify critics who panned the remake, while piquing the interest of moviegoers looking for a good scare. The film, which centers on a family that moves into a haunted Long Island, New York, home where a series of grisly murders took place, dropped from the #2 to #4 spot, pulling in

$8.1 million.

It seems as though moviegoers are beginning to leave "Sahara" high and dry. The film, which follows an explorer (Matthew McConaughey), his sidekick (Steve Zahn) and a doctor (Penélope Cruz) on their search for a treasure allegedly hidden in a Civil War battleship, dropped from #3 to #5 with $6 million.

The romantic comedy "A Lot Like Love" continued its attempt to woo audiences into theaters. The film stars Ashton Kutcher and Amanda Peet as a pair of "friends with benefits" who come in and out of each others' lives for seven years before realizing they are meant to be together. In its second week in theaters, "A Lot Like Love" dropped from #4 to #6 with more than $5.2 million.

Rounding out this week's new releases are "Kung Fu Hustle," dropping from

#5 to #7 with more than $3.8 million; "Fever Pitch," slipping from #6 to

#8 with more than $3.7 million; "Robots," sticking at #9 with more than

$2.6 million; and "Guess Who," sliding from #8 to #10 with $2.2 million.

Overall, ticket sales were down slightly from the corresponding weekend last year.

Next week, look for J. Lo's "Monster-in-Law," Jet Li's "Unleashed" and Will Ferrell's "Kicking & Screaming" to debut on the box-office top 10.

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