I was setting up my webdav (which I had not used since I upgraded my debian installation to etch from sarge) to talk to Windows XP and ran into a couple of unexpected issues.
AuthDigestFile becomes AuthUserFile
Somewhere in the upgrade to etch the AuthDigestFile directive went invalid (I recall I just disabled my webdav site when i upgraded). and is now AuthUserFile. Otherwise everything else stays the same.
XP forces NTLM Authentication
When I tried adding my web dav as a network place using my username / password the authentication failed and in the windows authentication box I saw servername/username instead of just my username. I did a bit of digging around various webpages and found a few client and a few server fixes. The easiest one for me was to create a new user in the form of user@server that bypassed the windows forcing NTLM authentication bug.
Etch denies DavLockDB
Finally I was able to connect but then I noticed that both cadaver (which I was using as a sanity check) and windows could not write to the dav. Windows reported the error a device attached to the system is not functioning. In Cadaver I was receiving an I/O error. It turned out that the apache2 user (www-data) could not write to the DavLockDB which was at /var/lock/apache2/DAVLock. I changed the owner of that file to www-data and from that point on the WebDAV was functional from both cadaver and WindowsXP.
The Windows XP authentication error was something I would have encountered but the sarge => etch upgrade path did not make it easy for my WebDAV. I am not sure if there was a reason why the DavLOCK database was no longer accesible to www-data (perhaps the default location for this database was moved) or why the Apache directive for digest authentication changed.