Or it could be ADHD... or a number of things. That's why it's helpful to see a professional to get an official evaluation. People on the forum can give opinions, but that's all they are, opinions. Opinions are no substitute for a real evaluation.
With that in mind, it could be aspergers, but seek out a professional opinion.
Have a look at the diagnostic criteria. If you google DSM IV and look for Aspergers that will give you a list of the behaviours that the professionals will be looking for when they observe your son.
I agree that if you are having these problems then it would be useful for your son to get an evaluation through Health. This will involve a number of professionals observing him and testing him. But if he does get a diagnosis, it will help you get supports for him in school. Also have a look on the autism and aspergers forums. You may see other parents posting similar problems to those that you have.
Temper tantrums are experienced by almost all children (and adults) on the autistic spectrum. But once you begin to understand how your child is experiencing things you will begin to see 'why' he is behaving like that. It is usually because of changes in how things are done or the sequence they are done.