Signaling that he fits into their long-term plans at least as the primary backup and possibly a starter at some point in the future, the Minnesota Vikings have signed quarterback Brooks Bollinger to a two-year contract extension through the 2008 season. Bollinger, 26, was acquired from the New York Jets last Friday in a trade, was entering the final season of his contract, and would have been eligible for unrestricted free agency next spring without the extension. Details of the two-year add-on were not immediately available. The deal with Bollinger is secures the backup spot behind starter Brad Johnson, who turns 38 later this month, and provides the Vikings further time to develop rookie Tarvaris Jackson, a second-round choice in this year's draft. The Minnesota coaches like Jackson, who played at Alabama State and was a bit of a surprise selection in the second stanza, but did not feel he was ready yet to assume the No. 2 spot on the depth chart.