Two big-time artists on opposite ends of the talent spectrum hit town tonight: Britney Spears tries to regain some semblance of respectable popularity at the E Center while B.B. King proves why he's the undisputed king of the blues at Kingsbury Hall. But joining heavyweight headliners on tonight's list of noteworthy concerts is Mirah and Tender Forever at Kilby Court. I suggest you hedge your bets on the relative unknowns. Mirah is a Portland based K Records artist with ties to The Microphones. She's currently touring in support of her latest release (a)spera with Rachel Blumberg (The Decemberists) holding down the back end. Fellow K Records artist Tender Forever will kick things off with her refreshingly honest unplugged-folk and lo-fi electro-pop jams. Fingers crossed for a live rendition of her Justin Timberlake cover.