Networked Printing Problem

[microbert42]

I cannot seem to figure out how to print to networked Brother MFC-7820N and Samsung ML-2151N.
I read through and followed the guides in the forum here and it all pretty much makes sense, however the solution usually is when NAT is not working, switch to bridged.
I have VB 3.0.2 running on Ubuntu 8.10 host with WinXP SP3 as guest.
Network is bridged with fixed IP using the IntelPro Desktop adapter.
Guest, host and printer are in the same subnet (192.168.0.x)

I have installed the manufacturers' Windows printer drivers same as on other Windows machines on the network. They are installed on a standard TCP/IP port with the printer's IP. I confirmed that the printer settings (IP, RAW/LPR printing, name are identical to the settings on other Windows machines that can print)
When I try to print a Test Page, the status is Printing and then Error-Printing. No output and no further hint on why... as usual in Win...

Here is what I have tried so far in VB:
Upgrade vom VB 2.0.2 to VB 3.0.2
All four combinations of PCNET Fast PCI adapter / IntelPro Desktop adapter and NAT/bridged network.

Oh, and I also tried on two different machines runnning Ubuntu 8.10 with two different installs of XP.

Networking in the guest machine seems to work. I can access the Internet, Samba Shares on the local net, I can see the printer admin pages at the printers' IP address and I can ping the printers. But, I cannot print...
Windows and other firewall software is disabled for now, so the ports should be open.

I tried sharing the printers from a local XP machine which can print to them, same result. Installation of the printers on the guest and installation of printer drivers works without hitch, but no printing.

I'm running out of ideas. Anyone found a solution to this problem before?
Any comment and help is highly appreciated.

Cheers, Uli

[vbox4me2]

Enable lpr byte count.