No, not the button, which yields that box,,,,in the scrolling list above, if file and print sharing is installed, you will see a file and print sharing -- double click THAT
Ok, I found it and disabled it and rebooted but no improvement. It really is hideously slow and gives the appearance of freezing up explorer when opening folders across the network from the XP machine. And yet, as stated previously, if I map the drive and browse the mapped drive it is normal.