To avoid having to specify the .dll file ending you can set DirectoryIndex in httpd.conf:
<Directory "C:/appfolder>
Options FollowSymLinks ExecCGI
AllowOverride None
Order allow,deny
Allow from all
DirectoryIndex myapp.dll
</Directory>
Alias /myapp "C:/appfolder"
This also cleans up the url so the .dll part does not show.