Slow save times from MS Office on Windows to XServe

Hello all, I have two XServe G5s, both bound to Active Directory. Whenever Windows users (Vista or XP) save MS Office (2003 or 2007) files to the server, it takes a very long time -- sometimes up to 10 minutes -- to save. This behavior only happens in Windows, and only with saving Office documents from within Office applications to an XServe. I have updated both machines to 10.4.11 with no luck. The samba log doesn't appear to contain any useful information. Any ideas?