You will always see collisons on Half duplex no matter how many things are attached. The reason is if the PC or what ever is connected tries to send data and the switch is tring to send data to the PC at the same time there is a collision. So lets say a user opens Outlook, it will communicate with Exchange, and while it is open it will always communicate at periods of time, now you open a document from a network share, it will go get it but remember Exchange and outlook are also communicating so there will always be a time where the switch and PC will try and send data at the same time, so there will always be collisions.
Hope that helps.
Mike
