These articles cover xcopy usage and switches:

• Xcopy; Windows Server 2003, Standard Edition
• Microsoft Windows XP - Xcopy

Caveats when using xcopy:

• NT4 - XCOPY /D Uses Universal Time, Not Local Time, to Filter Files

How I tend to use xcopy when migrating a file server:
xcopy /v /f /s /e /k /r /h /o /x /-y /z \\server\share\folder\