From the details you've given, I've calculated (via interest rate calculators you can find from searching the 'net) that your student loan rate is somewhere between 3% and 7.9%. (Principle=$56k, 14 yrs of payments, payment is between $410 and $550). But you'd be better to talk to your loan provider and find out the proper details on interest rate and loan structure from them as I'm just assuming 168 monthly payments on simple loan interest to arrive at those figures -- you don't give enough detail to do otherwise I think.
If your company matches $150 per month of your possible $250 contribution that is an instant 60% return. So, strictly by the pennies, you'd be much better off contributing to your 401k.
However, you should probably consider that most student loan debt is not forgiven if you ever declare bankruptcy -- it depends on the type of loan you have. As such, if I didn't have a way to continue to pay it for a long while should I lose my income in part or whole, that would be a priority for me to pay off just so I'm not at risk of facing consequences besides bankruptcy.
That said, it's pretty hard to give up that 60% immediate return on matching to your 401k. Perhaps you should consider splitting your extra $250/mo to get the max matching possible (is it the full $150 at $250 contribution or can it be lowered? i.e. is it 1-to-1 match capped at $150?) and then send any extra to paying down the 2nd student loan.