Your figures for Peterson's contract are a little off - he is guaranteed $17 million. From what I have gathered, Peterson also has roughly $14 million in incentives.
His contract, I believe, is only capable of being worth slightly under forty mill now, because of the voidable year, but for him to make that much he has to become the greatest running back ever; six million is tied to him gaining 2,000 yards and 20+ TDs, consecutively and concurrently, from 2008 to 2010. As Bears General Manager Jerry Angelo said, "[If Peterson met all incentives] t would be a win-win situation for the Vikings and for Adrian Peterson."
The seventh pick in the draft is going to have the better contract (read: cheaper) no matter what, but Allen has already proven to be an excellent NFL player and the draft pick is a gamble. I think it'd be hard to pay a Dwight Freeney type contract to any player (except Tom Brady) but I also think Jared Allen would be worth it more than Dwight Freeney. He would also, unlike a rookie, come in immediately and put up Pro Bowl calibre numbers as a starter. Allen's impact would be immediate and for the first four years (at least in my opinion) would be worth every penny of his contract, whereas a rookie would have a transition and would probably not produce as much as JA.
The seventh pick in the draft is also worth significantly more than any two pick combination the Vikings are capable of packaging to get Allen with the difference being a mid-to-late second rounder (if you want to go by the trade value chart). It's most definitely worth more than their 17th (950) and either one of their thirds (the 73rd is worth 225), so I may try to get something else out of the Chiefs (maybe a swap of picks in the third round, our third, not the one from Oakland).
It's tricky bidness, this here armchair GMing... makes me glad I don't have to do the real thing.
