'96 Mercury Cougar XR7

Hi guys :)

So the check engine light came on, and I used the OBD2 Autoscanner to diagnose the problem, and here's what I got;

-P1443 (Manufacturer control. Auxiliary Emission Controls)

-P0171 (System too lean [bank 1])

-P0174 (System too lean [bank 2])

Is it almost certainly just a bad O2 censor, or could it be something worse (more expensive)? If it IS just a bad 02 censor, is that something I can fix myself, or should I have it taken to professionals? How much would an honest mechanic normally charge for that work?

Thanks for any help you can provide. Trying to get the bloody thing smogged so I can register it. >.<