The "New Scientist" magazine volume 207, number 2769, dated 17 July 2010 page 14 has an article titled "Single star count ups odds of aliens."
"Solitary suns like ours are not as rare as we once thought, boosting the likelihood that there are other planets on which life has evolved.
"Surveys have suggested that most systems containing a star the same mass as our sun have two or more stars orbiting each other. But when Deepuk Raghavan of Georgia State University in Atlanta and colleagues looked at 454 such stars, they found that 56 per cent were single like our sun and just 44 per cent had a stellar companion...Their study will be published in the Astrophysical Journal.
"Single stars provide a stable planetary system where life is more likely to evolve. Planets can form in multiple star systems, but the gravity of the additional stars can hurl planets into their parent star, says John Chambers of the Carnegie Institution for Science, based in Washington D.C."