It sounds like you're wanting your workgroup to function like a domain.
A workgroup are a poor-man's domain.
Domain = 5-star hotel.
Workgroup = Motel 6 in the ghetto.
The only security options you have on a workgroup are share permissions, NTFS permissions (if using Windows), and the individual user accounts on EVERY SINGLE COMPUTER in the workgroup.
Turn off Simple File Sharing first (My Computer -> Tools -> Folder Options -> View tab -> turn off last check box "Use Simple File Sharing"). You CANNOT, I repeat, CANNOT do this with XP Home Edition, Vista Home Basic, or Vista Home Premium! (good thing you have XP Pro)
Let's say you have a workgroup like this:
COMPUTER1
User Accounts: Mr. T, Chuck Norris,
COMPUTER2
User Accounts: 50-Cent, Snoop Dogg
COMPUTER3
User Accounts: Slayer, White Zombie
COMPUTER4
User Accounts: Kelly Clarkson, Carrie Underwood
Let's say COMPUTER1 has a folder on the C drive called:
C:\I Pity da foo
On that share, the following permissions are set:
Share:
Administrators: Full Control
Everyone: nothing
Users: Read
NTFS:
Administrators: Full Control
Mr. T: Full Control
Chuck Norris: Read
SYSTEM: Full Control
Let's say Kelly Clarkson on COMPUTER4 wants to access that share using \\COMPUTER1\I Pity Da Foo. She can't get in without Mr. T's User Name and Password (or Chuck Norris' if she just wants to read what's there).
Of course a new account called Kelly Clarkson with the EXACT User Name AND Password can be made on COMPUTER1 to get into the share. From there, Kelly Clarkson would have to be added to the Administrators group or Mr. T would have to add "Kelly Clarkson -> Full Control" to the Share or NTFS permissions.
See how messy this can get? Everyone controls their own stuff on a workgroup.
