i don't have a digital, but i do have a moultrie feeders game cam II, i use a 6 volt rechargeable powersource(or powersave, i can't remember the name?) battery, and always get atleast 2 weeks out of it, even in single digits, only way cams could last longer is if they were run off of a little motorcycle battery.
can't complain about my cam, great pics, no matter the temp or weather. i think moultrie is the best bang for the buck. i have had my camera 2 years it has taken well over 1000 pics and is still going strong, just finished up the 6th roll of film in 5 days. i am going to get one of the digitals though, due to costly film developing.