One site that I havn't used but have heard is reliable is sportsbook.com.
These are the odds that they give relating to the Vikings. In my opinion odds makers are the most accurate predictors of what will happen, mainly because they put money on it.

I'm no expert on sports gambling but this is how I understand the lines. +3 means the team is given 3 points, so if the I pick the vikings and the line is +3 if they lose by one or two points I still win, even though the vikings lossed. If they lose by 3 it is a push and I get my money back. If the packers have -3 they have to win by more than 3 points, a 3 point win would be a push.


week 1





line
vikings





+3(-120)
packers





-3(even)

week 2
colts








-3.5
vikings






+3.5

10/6/08
vikings






+3
saints







-3

10/19
vikings







+2
bears








-2

11/9/08
packers







+3
vikings







-3

11/23/08
vikings







+6.5
jaguars







-6.5

11/30/08
bears








+4.5
vikings







-4.5

12/28/2008
giants







+3
vikings







-3

superbowl early line
afc










-6
nfc










+6

2008 NFL Regular Season Wins - Team Must Play 16 Games (A Tie is Considered a Loss)
Vikings
over8.5(-150)






under8.5(+120)

On games with a money line I believe it works like this. A $100 wager on a + number pays that amount(if you bet $100 on vikings to win superbowl you would win $1800). If it is a negative number that is the amount you would have to bet to win $100.

Odds to Win 2009 Super Bowl XLIII - Tampa FL
Feb 01, 2009 20:00 PM
vikings

+1800
packers
+2500
bears


+3500
lions



+8000


Odds to win 2009 NFC Championship
Jan 18, 2009 19:00 PM

vikings +700

Odds to win NFC north

bears


+300
Lions


+600
packers

+200
vikings

+125