VirtualBox: port forwarding

My host: windows XP
My guest: ubuntu 8.04.1

To redirect all connections from port 80 (www server) of the host machine to port 80 of theguest operating system being I used the following commands in windows xp console: VBoxManage setextradata "ubuntu-server" "VBoxInternal/Devices/pcnet/0/LUN#0/Config/Apache/Protocol" TCP
VBoxManage setextradata "ubuntu-server" "VBoxInternal/Devices/pcnet/0/LUN#0/Config/Apache/GuestPort" 80
VBoxManage setextradata "ubuntu-server" "VBoxInternal/Devices/pcnet/0/LUN#0/Config/Apache/HostPort" 80
"Apache" is an arbitrary name, and "ubuntu-server" is the name of my virtual machine with Ubuntu.

Ports can be redirected only when VirtualBox is turned off.