clincoln777, try not to let it get you too frustrated. Everything seems impossible, if you don't know how to do it. IT stuff requires specific knowledge, and you either know it or you don't. At any rate, I feel your pain. I do this stuff for a living and still run into walls sometimes.
In my opinion, the EASIEST way to get this working is to create that same "signons" on all machines. Then you can assign specific permissions to the signons on the local machine(server with the files to share). When someone uses that signon on their machine, they should automatically have access with the correct permissions on the server machine.
I have to admit, I haven't actually done this with a win 7 to win 7 connection, but I know it works for me perfectly between Win 7 and Win XP, and also between Linux (Samba) and Win 7....and also Linux and Win XP.