This is my understanding based on my reading of the book of Acts and the four gospels:
Prior to pentecost the holy spirit was given to believers on an individual basis for specific purposes and was not a permanent indwelling.
People who came to faith in Christ after pentecost received the holy spirit at the same time as they believed and accepted the promise of salvation.
People who believed prior to pentecost received the holy spirit either on the day of pentecost or when they had hands laid on them by someone with apostolic authority. They did not have to do anything to receive it, it was a gift and was just given in a straightforward fashion.
Therefore we (i.e. all people beyond 100 AD given the lifespans of the time) received the holy spirit indwelling us when we believed.
This does not preclude the command to be "filled with the spirit" which has nothing to do with the spirit indwelling us, but is more to do with "not quenching the spirit" and allowing God control of our lives via the work of the holy spirit.
You see, a doctrine of baptism of the holy spirit seperate from conversion can have only two possible practical implications.
Either:
1. Not all Christians have the holy spirit indwelling them and there are therefore two classes of Christian.
or
2. Only Christians who had a verifiable supernatural experience of the holy spirit are really christians, and the only way to get the verification is speaking in tongues.
Either way its pretty devisive and condemnatory.
The "new wave" Christians I have come across say that they don't believe in a baptism of the holy spirit but they believe in the gifts. However, every one of them I have asked to explain in details what they believe ends up expounding position #1: that there are two classes of Christian.
