Of course this path is not valid. Web works with paths relative to the site root directory which is mapped onto URL with domain name without sub-directories. Every absolute path written starting with URL schema and domain name is mapped to the file system absolute path depending on the root path. Relative path is relative to the location of the referring page.
This is explained here: http://msdn.microsoft.com/en-us/library/ms178116.aspx
As to the absolute path in terms of server-local file systems, such paths are not accessible by the HTTP server at all.