Yeah, just start Windows Sharing (Samba) in Server Admin.
If you haven't fooled around in the sharing in WorkGroup Manager, the same sharing applies for both AFP (Mac) as SMB (Windoze).
If your PC and Xserve are not configured otherwise, both belong to the workgroup "WORKGROUP" (duh..
), making life a little easier.
Then goto your PC and press, START >> Run....
Type in that window: "\\<IP ADDRESS OF Xserve>"\ ,and it should ask for a username and password.
BTW...
Your Mac OS X Client can test if that Xserve is correctly setup for Windoze-sharing:
Choose "Connect to Server.." (COMMAND - K), and type the following:
"smb://<IP ADDRESS OF Xserve" , and it should ask for authentication.
Note the difference in backslash and forwardslash between PC & Mac while accessing the SMB Share.