Check what funds are offered in the plan. I have Fidelity and I'm perfectly happy with them and they can be just as good as Vanguard. Honestly, they have better customer service and great funds. Just stay away from the professional management fees and high expense ratios, and you'll be fine.
http://www.bogleheads.org/wiki/FidelityIf you don't have any good options, go with the lowest cost expense ratio fund that aligns with your AA, and you can always roll it over once you leave that job to either better funds (Spartan series rocks) or over to someplace like Vanguard. The main thing is to make sure you're saving and reducing your taxable income at the same time in a tax deferred account.
The Fid Freedom fund has an expense ratio of .78%, and has a breakdown of roughly 65% domestic stocks, 25% international stocks, and 10% bonds. Very aggressive right now since the investment horizon is pretty far out so it's going to probably perform pretty well for you. It isn't a dog of a fund for someone young with time ahead of them and it's a fund that will automatically rebalance itself. I've seen much worse offerings. Sure, you could pay much less on the expense ratio, but if that's the best your plan offers, you'd be okay in there.
But do check to see if any of the Spartan funds (see the link) are offered as those are the super good index funds that match up with Vanguard's offerings. (I was lucky that the Spartan total stock market index is in my 401k)