If you have the latest Service Pack, you can change the default TCP ports (721-731) for LPR connections. A registry hack will allow ports >1024 to be used for LPR connections (this deviates from RFC 1179). The registry setting is configured on a per LPR port basis. To implement, navigate to:
Add Value name IP address of LPR printer as type REG_DWORD. A data value of 0 uses the default (ports 721-731) while a data value of 1 enables ports >1024.
At a minimum, you need to stop and restart the spooler service. Type:
net stop spooler
net start spooler
If this doesn't work, a reboot is required.