Payoff CC with student loans? Then invest or pay off loans?

I am using extra student loan money at 6.8% (mostly unsubsidized) interest rate to pay off my credit cards (about 25K) worth. What should I do when I get a bunch of other cash? Pay off loans or invest? I will soon be getting $5K cash and will probably get some additional money for freelance jobs, while I am in grad school (MBA). My wife and I would like to buy a house at some point in the next few years. So what do I do with the cash? Invest it (I typically return about 20% yearly on individual stocks...obviously riskier so maybe index fund?) Put it in a high yield savings account? Other thoughts? Some have said I should immediately make payments on my student loan...seems to me if I can beat the 6.8% on the student loan I should save the money for the house. (p.s. lest you think I am irresponsible with the 25K in debt their are valid reasons I won't go into..I am annoyed by it but it was mostly unavoidable)