Hi K.,
This is a frustrating issue, because you don't know what information to believe and the government has pretty much made the vaccination decisions for you (you have to vaccinate). I would pick up "The Vaccine Book" by Dr. Sears'. It gives information in an objective way "this is what we know... this is what we don't know... this is what to look out for, etc..."
Massachusetts requires that all children are up-to-date on their vaccinations prior to entering daycare or school, so we had not choice in whether or not to vaccinate our son. However, we decided to split up the vaccinations so he only got a few at a time. This meant that we had to go back to the pedi every month instead of every 2 months, but I think it was worth it to ensure that he was only being injected with the lowest possible amounts of aluminum at each appointment.
The issues about aluminum toxicity are explained in the book, but in a nutshell, aluminum in small doses is metabolized through the kidneys and expelled from the body via urine. If too much aluminum is ingested the kidneys can't process all of it and it settles elsewhere in the body, such as the brain. (this is why it has been linked with Alzheimer's) Each vaccine has a "safe" amount of aluminum, but there has been NO study to determine the effects of all the aluminum that is injected into an infant when multiple shots are given at one time. For this reason, I would spread out the vaccinations as much as possible if you can. I would also ask that the pedi use vaccination brands that have the lowest levels of aluminum and other toxins. (This is all covered in the book.)
Good luck!
J.