Ron,
The _vti folders have to do with the FrontPage Server Extensions.
When you publish directly to the web server using
http://, you are actually
connecting to the FrontPage Server Extensions. This also is the case when
you work locally with a web server as well (basically it's simply the same
issue) unless you're working with a website that is accessed through the
filesystem.
Don't delete the _vti directories. They hold meta information about
the web. In other words, they contain data about the files located within
the particular web. This information lets a client determine which files are
newer for publishing purposes. Deleting these directories can lead to
instability and inability to publish.
The aspnet_client folders are for the client scripts used by asp.net
and shouldn't be deleted. Usually if you can see them it's because they were
specifically put there to make things work, they're a placeholder that
points as a virtual directory to the scripts in the windows directory, or
were created when asp.net was setup for the server. In any case, it's safest
not to remove them as you're various controls could have trouble working if
they can't get at the correct scripts, especially for things like
client-side validation.
