Goal:

provide a 'no-software' method for 'less technical' users to access password protect ftp location from Win7 and Vista (existing approach for WinXP works).

'No software' method to mean without installing additional software (e.g. FileZilla, WinSCP) - the solution is supplied to external non-technical users.

WinXP (works):

Using Windows Explorer, WinXP supports non-technical ftp access by pasting:

ftp://username:[email protected]

into the address bar.

The remote ftp site's files / directory structure becomes available and can be copied to / from easily (in the style of local file copy / paste) by a 'less technical' user.

Win7 / Vista (doesn't work):

Pasting the same URL into the Windows Explorer on Win7 or Vista causes an error:

An error occurred opening that folder on the FTP server. Make sure you have permission to access that folder.

Details: 
The connection with the server was reset.

Notes:

a) The same username/password/server typed from the (DOS) command line achieves access to the server, but this is a more 'technical' solution than desired. I am looking for a WinXP equivalent solution.

b) Under 'Control Panel' / 'Internet options' / 'Advanced' tab - the boxes for 'Enable FTP folder view' and 'Use Passive FTP' are ticked (enabled)

c) Adding an inbound firewall rule for local port 20 (TCP) was attempted with no difference in results (i.e. failure)