HTTP PUT request return error code 501

Hi,
On a Win 2003 enterprise server with SP1 and IIS 6.0, when my program tries
to execure HTTP PUT request, IIS returns error 501. If WebDAV is enabled then
this works OK. Customer doesn't want WebDAV to be enabled so how can I get
this to work ?

I have checked the permissions on the folder where PUT is supposed to write
(I opened up to EVERYONE), i've also checked the Directory Security and have
set Basic and NTLM on the VDIR in IIS.

Thank you in advance
-Jignesh