Why is there a ton of network traffic when using Win7 to connect to my Samba share?

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http://serverfault.com – I have an Ubuntu server running samba that several Windows clients connect to. On my machine, I have Windows 7 and Gkrellm, which shows me different statistics about my computer, including network traffic. I notice than when I open the share for the first time I get sustained 3-4 MB/s network traffic to the server (I think this is just maxing out my wireless) without doing anything. I can exit out of the window with the share and it keeps going. I'm confused on what is going on. Why is there so much traffic on the first connect? Why does it stop? Is there any ay to turn it off? If it matter (HowTos)