TDC can only read from the web server. So maybe that won't fit the bill.
XMLHTTP can read and write back, but the write back is a POST so you'll need something to accept the data... like an ASP page.
I'm not sure what FTPOpenFile refers to, but there are components that'll run client-side that can do FTP. Of course you'll need FTP access to the server then too as well as HTTP.
I think XMLHTTP is capable of a WebDAV PUT as well, but this takes us into even deeper territory.
What are you trying to accomplish? Maybe more information will get you a better answer.