kubora666, flu shots only protect against common annual flu strains, not bird flu.
See, when a virus enters your body, your immune system has to find out what antibodies to use against it. This is a process of trial and error, but once the correct antibody is found, your immune system will "remember" that antibody, so any time it detects the same antigen again it will automatically use the correct antibody against it. In this way, once you've had a certain virus, you will forever be immune to that kind. Vaccines work by injecting dead virus into you, causing an immune response so your immune system can identify the correct antibody ahead of time without you actually getting sick. The problem is that viruses are constantly evolving, so the structure of their antigens (proteins and/or polysaccharides on the surface of the virus) are constantly changing, making it unrecognisable to your immune system and the process of identifying the correct antibody has to start all over again -- this is why you have to get a new flu shot every year, to account for the changes in the virus. This is also why it would be impossible to make a highly effective vaccine for bird flu before the virus mutates into... well, whatever form we're afraid it's going to mutate into. We don't know what antigens to use in a vaccine to imitate the virus.
EDIT: BTW, the way vaccines work is also why it's impossible to make a vaccine for the common cold (like so many of us wish existed!) There are around 121 different viruses that can cause cold symptoms... imagine how hard it would be to create and keep current a vaccine that would protect you against all of them! As you catch them, though, you naturally become immune to them one by one, which is why younger people have more colds per year on average than older people do. Think about your grandma... she doesn't get colds much anymore.