Other than the state sponsored 401k you can choose from a variety of indpendent (403B) vendors. 403b is a tax code just like 401k- the numbers are meant to be confusing but don't worry about it. Your independent vendors are the charming folks who come to your school , barge into your classrooms and try to convince you that there company is the best in the world (companies like ING, AXA, LSW, GA, Prime America...).
The majority of these reps are good folks who mean to do well and help you as much as possible. The problem is that they can only place you with products there company offers. This means that the ING guy can only sign you up for ING. The AXA guy can only work with AXA... IF there company has the best option for the type of plan you like, then you will be well taken care of. The downside should be obvious- IF you have a rep from one of these companies they will more than likely NEVER tell you to go to another company. In the market these types of agents are called 'captive agents', because they are captive to the line of products their company offers.
There is only one company that is permitted into your schools who represents EACH and EVERY vendor, UTah Pension Services. They can speak to you concerning ING, AXA, LSW etc...
The advantage to you- unbiased opinion and a frank analysis of products across every company resulting in your obtaining the best option possible.