News wrote:

When I connect the phone to my Netbook (running XP!) via USB lead, I
can see it and access it as an attached device,just like a USB stick,
camera etc.

OK.

When I connect the two wirelessly, via the home network, I can 'see' the
Netbook from the phone, and access shared files.

That's because the PC is acting as a file server, and ES explorer is
acting as a CIFS client.

What I cannot do is see the phone from the Netbook wirelessly, through
My Network Places, Entire Network etc.

Your PC is a CIFS client, but Android doesn't act as a file server.
That's why people have suggested mounting over SSH etc.