had my first real problem w/ my PF last night. out in the chicago suburbs, the temp was down around -5F. my truck wouldnt start

. hooked it up to a wall charger, turned off anything that could draw power at the start, gave it another try, and it finally started... a little reluctantly though. dont know if it was the charger or the load removal, but it did start.
anyone have cold starting issues? these kind of temps arent that common around chicago, but i dont want to be stranded somewhere where i dont have access to a wall charger or a jump start. who's upgraded their batteries? optima red top? others suggestions?
~mike