2 liter starter with 4 month old yeast?

I'm making a Belgian Dubbel from a Northern Brewer kit. I smacked my Wyeast pack and started brewing the starter. I saw no swelling after 5 hours but decided to throw it in my wort anyway. It's been 24 hours and I have no activity at all. I noticed the date on the yeast was for October 2012 so it looks like the yeast is a little old. Is the 2 liter starter going to be too much stress for the old yeast. And is there any hope of my yeast taking off. I'm somewhat worried about contamination as well with lack of yeast activity. Thoughts?

There will be some viable yeast. Google Mr. Malty yeast calculator. You will see there a place to input the yeast date and calculate viability and starter size. Never brew without Mr. Malty.....

2 Liters is a good size for an ale. Your yeast is not that old. But check with Mr. Malty for details.....

+ 1 on checking Mr. Malty, or yeastcalc.com. I've used months old packs before, but viability always suffers. I'm more than willing to bet that for a Dubbel, 2L would be cutting it close even with a much fresher pack, so you'll probably have to step that one up. If you're stepping up, yeastcalc is probably more useful (I use yeastcalc if I'm stepping starter up, I use Mr. Malty for one step starters or repitching).

Mr. Malty says that based on Oct 31 as a manufacture date for the yeast I would have a viability of around 40 percent and would need a starter size of 4 liters with one smack pack. So I'm thinking after the initial starter is fermented out I'll decant and dump the wort and then add another 2 liters of freshly brewed wort. This should give me more than enough viable yeast right?

Yep, that's how I'd do it, it's called "stepping up".

yeastcalc.com is better for stepping up. they will give you the same results but on yeastcalc you can enter multiple steps

Definitely use yeast calc and do a two step starter.

Mr. Malty over estimates viability in my experience. You are probably much closer to 80% viable. However, although the yeast are viable, the vitality may be low. It could take a couple days for them to get going. Glycogen reserves are likely low making sterols hard to produce which makes cell wall permeability low.

The two most popular yeast calculators may give you a false sense of accuracy. For example, cell counts show I typically get twice as many cells generated as the calculators think I should get. Starters seem to follow the old brewers rule of thumb that 10 billion cells are generated for every litter of wort and every degree Plato. So if you made a 9 Plato wort (1.036 SG) then you should have about 180 billion new cells in addition to the 80 billion you pitched that's 260 billion, but you might want to round down to about 250 billion cells. (Round down assuming you aren't trying to under pitch like one might for a Saison)

See here for a Mr. Malty story:
http://woodlandbrew.blogspot.com/2012/11/counting-cells.html

And here for viability of yeast stores in the fridge:
http://woodlandbrew.blogspot.com/2012/12/refrigeration-effects-on-yeast-viability.html

Alrighty thanks all. I am still concerned about possibly infection as well though. About 24 hours after throwing my smack pack in my wort. I noticed a suspended white ropey goo substance floating in the wort. It rises to the top when I swirl it. I've read that it should be too early for visible signs of infection but I'm just wondering what it could be. It looks too white and clear to be yeast. Maybe it's the yeast nutrient? I'm just concerned about throwing this in my beer without knowing what it is. By the way, the yeast smells fine and I did have some activity this morning.