Installing ubuntu from Internet via usb key

Dammit, after 2 weeks vacations without using my main desktop pc, ubuntu natty stopped working. Don't have time to troubleshoot, so rolling back to LTS lucid.

Got the netboot.tar.gz file from:
http://archive.ubuntu.com/ubuntu/dists/lucid/main/installer-amd64/current/images/netboot/

and then wrote it to a usb key with imagewriter
sudo apt-get install usb-imagewriter
sudo usb-imagewriter
info from:
https://help.ubuntu.com/community/Installation/FromImgFiles

boot from usb and install