if it isnt working you can always set up and .htaccess file specifying the index.html as the DirectoryIndex. But it apache by default looks to index.html as the defaul html page.
If you load up the url with index.html tacked on the end does it load?
You should have this entry in your httpd.conf also
# DirectoryIndex: sets the file that Apache will serve if a directory
# is requested.
#
# The index.html.var file (a type-map) is used to deliver content-
# negotiated documents. The MultiViews Option can be used for the
# same purpose, but it is much slower.
#
DirectoryIndex index.html index.html.var
Make sure you specify the DirectoryIndex correctly. Or if you have changed it set it back correctly