MUSTWORTHINESS She could have spent the rest of her career portraying adorable fashionistas -- see ''Sweet Home Alabama'' and ''Legally Blonde''. Instead, Witherspoon will star as 19th-century temptress Becky Sharp in Mira Nair's very original adaptation of the Thackeray classic ''Vanity Fair.'' As for summer vacation: She's spending it in her native Tennessee, playing beloved crooner June Carter Cash in the Johnny Cash biopic ''Walk the Line.''
ON HER MUST LIST ''I always, always wanted to be Dolly Parton ever since I was 6 years old.''
ATTENTION, CASTING AGENTS ''I'm desperate to do a scary movie. I watched 'Seven' over and over. I love M. Night Shyamalan. I'm so excited to see 'The Village.''' (So are we; see No. 102.) ''I just love to be scared. For me that's the only time I can really forget I'm watching a movie.''
NEXT ''Vanity Fair'' opens Sept. 1.