Thanks for all the input. I am just going to insulate it and go with it.Well, according to http://www.mrmalty.com/calc/calc.html, you need 283 billion cells for a 5 gallon batch. Even if you had a brand new pack at close to 100% viability, you'd be grossly underpitching. You should consider making a starter or buying a couple more packs.
I am hopfully going to hit 1.083 OG with this beer and I was wondering if it will be ok to just pitch two bags of liquid yeast rather than making a starter because I don't have time to make one before the weekend. The liquid yeast I used last time said it started out with 500 billion* cells in the bag.
Edit: 100 Billion