Hi Katmartian,
First, before getting into whether you should pay down your student loans or invest in your 401(k), make sure that $700 line of credit gets paid off. This is the top priority.
I am a little confused by your numbers. You say that you make about $2,000/mo or $24,000/yr gross, but you contribute 15% of your pay to your 401(k), which is also $400/mo? 15% of $2,000 is $300/mo. Otherwise, if we assume that $400 is 15% of your salary, then you make $2,666/mo or $32,000/year. I'm asking because I think it makes a difference in your situation.
I would weigh the interest savings benefit of paying off the student loans earlier against the tax benefits of your 401(k) contribution and the student loan interest deduction. You will pay more in taxes if you reduce your 401(k) contributions to pay off your student loans. The question is whether that increased tax burden is worth the interest savings and/or the peace of mind of not having loans. You'd need to run the different scenarios to answer this.