RB's I dont really like any of those options, but if I had to pick, I'd probably go with Shonn Greene, he will probably get more carries and does really well with making those carries count. Hart is okay, but only IF Addai and Brown are out, and even then I still like Greene more. Bush is relegated to spelling DMC, so he'll be extremely limited in carries. The lawfirm is a great between the tackles back, but thats where the Vikes are strong. He may be good for 30-40 yards and a TD, but the TD isnt necessarily a guarantee.
WR's, Id go with Britt and Williams. Williams has a great matchup, and besides Winslow is the only other option in that offense. I like Britt even though SD has a pretty good pass defense, mainly because I dont trust Evans. If you do trust Evans, he has a better matchup, but I think Britt has more natural talent, and a better run game.