Just to save you re-inventing the wheel, but emacs has a mode to do this already - it is called ange-ftp and comes with the standard emacs distribution (try opening a file called /user@host:file and see what happens). If you want a windows editor which does this then GWD is good.

Better if you want to do this securely you can use the rcp package for emacs. You can get this package here. Though it is called rcp, the package allows many ways of editing remote files including ssh & scp.