Network printing

[Rein]

Hi,
I wish to print from xp to Ubuntu.
This is the setup:
Computer A: dual boot XP and Ubuntu 9.10
Computer B: dual boot Win 7 and Ubuntu 10.04 + Printer (Dell_V313 usb)

XP prints to WIN 7
Ubuntu 9.10 prints to Ubuntu 10.04
Have not tried Ubuntu 9.10 to Win 7 (less important)

But whatever I try I can't get XP (SP3) to print to Ubuntu 10.04
It just can't find the printer.
http://<hostname>:631/printers/<printername> does not work
Although http://<hostname>:631/printers comes up with the right printername.
Can anyone help?
Rein