FIXED: (well, maybe for me but still...)
1st off, "A.Nonymous" is acting like a dick.
2nd, In Googling this specific issue for myself, not wanting to run a 40ft CAT5 to where I was working, I plugged in my Nexus S via USB to a freshly installed Win7 Home Premium x64 box. Drivers installed automagicly. I turned on USB tethering WHILE having the phone connected to my home Wifi.
At first, I didn't know if it was connected via 3G or my home Wifi, but as soon as I typed in my wireless routers IP address in my browser & was able to log in, I knew I was on my home's network, not my carrier's 3G connection.
I can't say this will work for any other person on earth, I'm just letting you know that for me, it really is acting as a wireless adapter via USB tethering.
NICE!
Hope this info helps someone else.
MetalGeek.