ive gone through several tutorials and everything seems to be configured properly, my vista pc sees my Ibook, but when i click on my ibook in the network window it asks me for username and password, which i would assume would be my login information for my ibook, but when i enter that, it says its invalid, so my question is how do i determine exactly what it wants as login information. Ive tried all logical possibilities. thanks in advance.

I have the same issue with Ubuntu. I try to log into Ubuntu from my windows network and it asks for a user name and password. I enter the username and password for the Ubuntu computer but it doesn't connect. I can access the windows computers and a Mac on the network from the Ubuntu computer. I am missing something in the network setup, or users and groups. I don't have an answer as yet but will keep you posted.
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Did you create a Samba user on the Ubuntu machine with the same name as the Linux user? Something like "smbpasswd -a username" and "snbpasswd username"

When logging in from the Windows computer, you may have to give the Linux machine name as the login "domain". Sth like UBUNTUHOST\username

Try just a normal user id / passwd identical on both systems.
I find that when my Linux is running AND the same user-id active on both, Samba connects easily.