The new guidelines for core vaccines are puppy shots, boosters at one year and then every three years (some believe that is a compromise and protection lasts even longer). But, these are guidelines and every owner should discuss this with their vet and decide what is best for their dog.
http://www.healthypet.com/library_vi...x?ID=196&sid=1
You can download the guidelines here...
http://www.aahanet.org/About_aaha/Ab..._Canine06.html
I found it very interesting.