Windows is "chatty", shall we say!
It has network diaoreahia pretty much constantly.
In the old days of NetBeUI and Apple talk a couple of machines could saturate a whole subnet if some idiot tried to plug them into a managed network without talking to the sys admin. It was one of the factors we used to watch for to spot when users had plugged thier own laptops in. I could never be bothered arguing so I used to just ban the offening MAC address from the DHCP server and switches/routers.
You can cut the traffic down by going in and turning off several services but in your situation I would just leave it as it is. Its one thing spending a couple of days getting the perfect machine when your going to roll out a couple of thousand installations but for a one off its not really doing any harm on its own ickle subnet