The problem I see with heading to the stores after the outbreak is because every person who is not prepared will be heading there. Talk about a crowded place and not enough supplies to go around. Lets face some simple facts:
#1 If you have no plan, your chances of survival, just dropped dangerously low
#2 If your plan involves going to a public place, that will be the target of the rest of survivors, for example-sams club, home depot, grocery store, your chances of survival just dropped. Not only will you have the undead to defend against, you will have tons of others that are thinking along the same lines and lets face it, it will be a life and death battle for control of the store.
#3 People that over prepare, for example try to take too much stuff, will end up dead as well. Too much stuff will slow you down. And slow=dead. There was A LOT of talk on the SKS boards about how much ammo to carry. Well 1000rds takes 3 50 cal ammo carriers. Its relatively heavy and carrying that will more than likely be about the limit you can carry for an extended period of time. Even with backpacks, shoulder bags and a drag bag, weight=slow=dead. Along with the ammo, you will need the weapon, back up weapons, clothes, blankets, short food supply, water (at 8pounds a gallon) etc etc.
#4 woods/mountains=safety. Lets face it, the undead will gather around populated areas or their food supply. The few that do wander or get lost in the woods/mountains, will be easy targets. The best way to survive will be to avoid as many as possible.
#5 Not only will you have to survive the undead, you will have to avoid rogue groups of people preying on the survivors, you will have to avoid the govt groups that will definately be rounding up survivors and taking them to "safe zones", but in essence will be test subjects for the anti-virus.
Now a lot also depends on what kind of zombie we are talking about. The early romero slow zombies with almost no body control? The rage type zombie from 28 days later? The new and improved faster zombies from the dawn of the dead 2005? Will it be the zombie type from I am legend, that cant go into the daylight? What about animals? The movies lead us to believe that they will be imune to the virus, will this be the case? Or we will be fighting against zombie squirrels, opossums and deer? I am legend shows that while a dog is good to have as a warning system, it can get infected just like humans and turn.