There probably aren't a lot of people out there that are still contesting fantasy football leagues, as many leagues ignore Week 17 due to the unpredictable nature of players sitting out and resting before the post-season.
For the Vikings, Adrian Peterson is obviously a must-start, as he is every week. Percy Harvin is a good bet for this game as well, as he seems to have some real chemistry with Joe Webb (7 catches, 100 yards on Tuesday against Philadelphia). If you have the Minnesota defense, you might want to give them a start as well. And if you're in one of those weird leagues that grants Webb eligibility as a wide receiver, he might be a good play to get some sneaky points that you typically can't get.
On the Detroit side, the only real starting recommendation I could make is Calvin Johnson. The Vikings have never matched up well against Megatron, and with the Detroit running game likely getting shut down by the Vikings defense, the Lions are going to have to air it out in this one.
Other than Johnson, I don't think there are too many recommendations I can make for Detroit.
And there is your fantasy football focus for the game between the Minnesota Vikings and the Detroit Lions.