Janet Jackson is going to have a lot of company when she performs during the halftime show at the Super Bowl on Feb. 1. CBS and sister network MTV (which is producing the musical interlude) announced Wednesday that P. Diddy, Nelly, and Kid Rock will be joining Jackson on the gridiron stage in Houston's Reliant Stadium. (AOL is the chief sponsor of the concert segment, whose full name is the AOL Top Speed Super Bowl XXXVIII Halftime Show.) The booking marks a return engagement for Nelly, who performed at the last MTV-produced Super Bowl halftime show three years ago, along with Aerosmith, 'N Sync, Britney Spears, and Mary J. Blige. MTV president Van Toffler touted the show in a statement, saying: ''With the distinctive music of P.Diddy, Kid Rock, Nelly, and Janet Jackson colliding, it's sure to be a powerhouse half-time that will appeal to all football and music fans.'' Colliding? Maybe the NFL should issue the performers some helmets and shoulder pads.