HELP! Windows 2003 Server Shared folder access

Hello,

I have a Windows 2003 AD Domain controller set up. I have some Windows
XP Home clients that are logging in locally, using the workgroup name that
is identical to the Domain name. I have created their accts. on the 2003
Domain server (same username and password).
They can browse to the shared folders and open documents, but I cannot
seem to give them Full access to the folder even if I add their username in
2003 NTFS permissions. What do I need to do on 2003 server to allow
non-domain members to access shares based on NTFS permissions??

Help...

Mark