On TV: Avril Lavigne, Ashlee Simpson, Dido

Pop acts on television this week include Avril Lavigne, who performs on ‘The Late Show with David Letterman’ on Monday, ‘Live with Regis and Kelly’ on Tuesday, ‘The Ellen DeGeneres Show’ and ‘Total Request Live’ on Wednesday; Ashlee Simpson, who performs on ‘The Tonight Show with Jay Leno’ on Monday; ‘On Air with Ryan Seacrest’ will have a reunion of the ‘American Idol’ finalists on Monday; Alanis Morissette, who performs on ‘The Ellen DeGeneres Show’ on Tuesday, ‘On Air’ on Wednesday, and ‘Jimmy Kimmel Live’ on Thursday and Friday; Mandy Moore, who appears on ‘The Late Show’ on Wednesday, ‘TRL’ on Thursday, and ‘Late Night with Conan O’Brien’ on Friday; Dido, who performs on ‘The Tonight Show’ on Thursday and ‘The Late Late Show with Craig Kilborn’ on Friday; and on Thursday’s ‘On Air’ and ‘The Tonight Show’, the newest American Idol winner will be on — which will be either Fantasia Barrino or Diana DeGarmo.