XP Clients Can’t Write to SMB Share

Hi, I am new to Mac OS X Server and a friend recommnded I ask my question here. A few days ago, I set up an Intel xServe with OS 10.5.4 (now 10.5.5). It is obviously not in production yet. I bound the server to our AD domain as a client so that I could use our organization's users/groups lists. I set up a share point with an ACL on a mirrored raid set and enabled AFP and SMB. For SMB, I configured it to recognize that the server is a Domain Member. Configuring protocol options, I turned off guest access for both, and disabled both FTP and NFS, despite those services remaining disabled. I tested out that I could then mount via both AFP and SMB the share from a Mac 10.5.x client, and I had no problem using either a server admin account or an AD account. From the XP machine, using an account that was logged in through the domain, I was able to mount the smb share by mapping the network drive without having a prompt for user/pass. I had set that AD account to be allowed Full Control of the share via the ACL. Oddly though, once mounted, I was unable to copy files to the share. Doing some further investigating, I tried setting the "Other" POSIX permission for the share to "Read/Write". This allows the AD user to copy files to the share; however, the files end up being owned by the user "Nobody" instead of the AD user putting the files onto the share. I am assuming something basic here (a "duh") that I am missing, but I can't find any reference online or in the Server Essentials book. I also looked through the Apple Forums and the Network Services guide without being able to find a solution. While I feel that I have it set up correctly, obviously I have not, hence the post. If anyone would be willing to lend a hand to newbie, in terms of a solution, tips, or things I could try, I would be very appreciative. Thanks in advance!