Rober McMurray has documented all currently available settings in his blog, it's a great resource and I have to copy it especially for my own memory.
The base registry hive is:
The know settings are:
| Value & Description | Type | Values | Default | |
| AcceptOfficeAndTahoeServers Specifies whether the WebClient service can connect to web sites that are running SharePoint or Office Web Server. | DWORD | 0 = False 1 = True | 1 | |
| BasicAuthLevel Specifies whether the WebClient service can use basic authentication to talk to a server. Note: Using basic authentication can cause serious security issues as the username/password are transmitted in clear text, therefore the use of basic authentication over WebDAV is disabled by default unless the connection is using SSL. That being said, this registry key can override the default basic authentication behavior, but it is still strongly discouraged. | DWORD | 0 = Basic authentication is disabled 1 = Basic authentication is enabled for SSL web sites only 2 = Basic authentication is enabled for SSL and non-SSL web sites | 1 | |
| FileAttributesLimitInBytes Specifies the maximum size that is allowed by the WebClient service for all properties on a specific collection. | DWORD | Size of attributes in bytes | 1,000,000 decimal (1 MB) | |
| FileSizeLimitInBytes Specifies the maximum size in bytes that the WebClient service allows for file transfers. | DWORD | File size in bytes | 50,000,000 decimal (50 MB) | |
| InternetServerTimeoutInSec Specifies the connection timeout for the WebClient service uses when communicating with non-local WebDAV servers. | DWORD | Time in seconds | 30 decimal | |
| LocalServerTimeoutInSec Specifies the connection timeout for the WebClient service uses when communicating with a local WebDAV server. | DWORD | Time in seconds | 15 decimal | |
| SendReceiveTimeoutInSec Specifies the timeout in seconds that WebDAV the WebClient service uses after issuing a request, such as “GET /file.ext” or “PUT /file.ext”. | DWORD | Time in seconds | 60 decimal | |
| ServerNotFoundCacheLifeTimeInSec Specifies the period of time that a server is cached as non-WebDAV by the WebClient service. Note: The WebClient service maintains a list of non-WebDAV servers that have been contacted. If the server is found in this list, a fail is returned immediately without attempting to contact the server. | DWORD | Time in seconds | 60 decimal | |
| SupportLocking Specifies whether the WebClient service supports locking. | DWORD | 0 = False 1 = True | 1 |
Note: After changing any of these settings you will need to restart the WebClient service.
Source: Robert McMurray's Blog
