Every gun-nut who says "why don't they just use their guns" when watching zombie movies needs to watch Dawn of the Dead. Best zombie movie eva!!! Little campy being made in the 70s I take it, but the remake that is being made should be ever better...
Anyway, I'd use a Saiga 12 gauge along with a 5.45 caliber AK if I coudl procure the ammo, a standard 7.62 model if not, and a good hicap pistol. I think the shotgun would be very useful for larger groups of zombies, remember you don't have to kill them with a headshot, their mobility is limited/zilch after you blast them apart pretty good with a shotgun giving you time to escape or whatever... Finish the immoblie ones off at your leisure with your pistol if they're in your compound and might pose a slight threat/annoyance (I'm thinking a Mall like in Dawn...) I think I'd snag something like a scoped M1A for longer range headshots from a safe position too. Oh yeah, and you gotta have a melee weapon, I think a nice Katana would work, how about a repro of the Highlander sword. What better to behead zombies with? lol...