Jim Cramer announced last night that he is bullish on Best Buy ( BBY), but advised investors to turn the dial on rival Radio Shack ( RSH). Last month, Cramer suggested buying Radio Shack on the heels of the mandatory digital conversion. But that trade didn't work, and he now says to sell and cut your losses. Instead, he says to look to Best Buy, which yesterday teamed up with TiVo ( TIVO) in a marketing deal. The two will form an alliance where Best Buy will heavily promote TiVo products in its stores and will attempt to bring TiVo's software and search tools to its own brand of electronics. TiVo will develop a version of its set-top box -- to be sold in Best Buy's 1,100 U.S. stores -- that will let the retailer advertise its products and services to TiVo subscribers on their home televisions. Financial details of the pact were not disclosed. Granted, Best Buy has had its fair share of static interference amid the recession. While the elimination of rival Circuit City should have propelled Best Buy's market share, in such categories as DVDs, it's losing out to cheaper competitors like Wal-Mart Stores ( WMT) and Costco Wholesale ( COST).