Our postseason prospects are better if Tennessee wins the SEC east.
That's the thing about conference championship games: the team that loses it is usually worse off come bowl time than the second place team from their division.
If we win out and Tennessee goes to the SEC championship game and gets slaughtered by LSU, we will go to the Sugar Bowl.
If we win out and Tennessee goes to the SEC championship game and beats LSU, LSU will probably drop below us if we don't lose between now and then because they would have been beaten by a relatively low ranked team. We'd both have 2 losses but Georgia would probably be the second SEC team chosen for the BCS.
If we manage to go to the SEC championship game and we lose, we'll probably end up in the Capital One Bowl.
So, here are the scinarios:
1.) Win out, but miss the SEC Championship Game: Sugar Bowl.
2.) Win out, go to the SEC Championship Game and lose: No BCS Bowl.
3.) Win out, go to the SEC Championship Game and win: Sugar Bowl.
So, for all our efforts in winning the SEC championship, the only thing we'd have to show for it is a trip to the Sugar Bowl, which is the exact same position we'd be in if we didn't go to the SEC championship game in the first place.
I'd rather take the guaranteed BCS bid than play in Atlanta and risk losing it.