Bad archive mirror using PXE boot method
You can save your mirror information in your kickstart file:
curl --url http://192.168.1.1/ubuntu
You can specify the kickstarter file in the PXE boot line:
append vga=normal initrd=installers/jaunty/i386/initrd.gz ks=http://192.168.1.1/ks.cfg ksdevice=eth0 --
You should use apt-mirror to create a local copy of the ubuntu mirror. It is about 40GB and will take all night to generate. Please see questions directly about each of these things for further details.