Hmm, its hard to say. Best bet would be to get the newer version of tDav from AOLserver CVS and try to integrate into OpenACS.
Note that Windows 7 does not have WebDav support anymore, so I am not sure how long that will be a viable option.
You can also research the WebDrive software which is not free, but it is what we recommend for everyone trying to use WebDav on Windows.
