Canon LBP 3500 Printer needs monitoring

My office few user use windows XP professional and few windows 7.
Most of them use Windows Server 2003. Because we are a software team.
Ok we have a network printer which we use always.
Our printer is canon LBP 3500 model.
Problem is that some user prints some personal documents. So we need to find out it.
We need to know when and who print what’s document in this printer, we want log file where this can automatically save, how can possible?
