Using Windows 7 when users use the "swich user" option to log onto the domain does any bandwidth from the previous user(s) who is/are still logged in get cut off or is it still being utilized as well?

Pretty simple to find out... Kick off a large download, switch user, wait 5 minutes and log in to check the download.

ETA -  easier:  start a ping /t and switch users, then log back in and check it out.

I have not done this, but at work we use a terminal that will error out if the connection to the host is lost.  After countless user switches I don't recall ever logging in and finding a connection lost error. I would guess connections are kept alive.

All the stuff that the first user had running is still running, just in the background where the second user cannot get to it.  If one of those programs from user 1 is downloading something large, it is still downloading while user 2 has the foreground process.

I assumed so.  Our network was getting hammered and the logged on users weren't doing it.

VLAN reset helped quite a bit.