Mr_CheeseYou would need to specify some rules before starting as on most maps 5v4 doesn't really work too well.
That goes without saying. ;) It's plain stupidity to play matches with unfair teams / settings. The more difficult the victory, the sweeter the taste of it. :D
if you need an extre played ask your next door nabior or some on from your school or work
Like Rnold said, dont forget Co-op mode. The bots arn't as good as real players but they add as many bodies as you need. Most likely they won't out fight you but it's better than running around for five minutes trying to find someone to shoot at.
That's true and there's the Intensity add-on out which was supposed to make the bots as good as Call of Duty... (I haven't tested it yet so I'm not sure on that one).