You posted you have activated the FTP services in the NT4 machine. That usually means you activated IIS FTP server, this one links to your Windows accounts (take care with Administrator!). Now, if the NT4 machine has also an IP address, that's all you need. Does the NT4 machine have a firewall? Allow IIS FTP to pass through.
On the XP machince just take the latest FileZilla Client, connect to the IPv4 address of the NT4 machine (NT4 usually doesn't offer IPv6) and use the Windows account login data. It ain't pretty, but should work.
On the XP machince just take the latest FileZilla Client, connect to the IPv4 address of the NT4 machine (NT4 usually doesn't offer IPv6) and use the Windows account login data. It ain't pretty, but should work.