Firstly download the netInstalltion ISO from ftp.wicks.co.nz
Burn off ISO then continue with setup.
When it asks for installation location enter the following FTP site details:
site: ftp.wicks.co.nz
directory: /pub/linux/dist/centos/5.5/os/i386
of course change os/x to your hardware version i.e. x86_64 if you have 64bit architecture.
Go with default installation - recommend to customise later.
Please Note: This will also work for later versions of Centos net installations i.e. 5.6 - just change the above directory location to the version you want to install
other netinstall versions:
Centos 5.5 x86_64 netInstall ISO
Centos 5.6 x86_64 netInstall ISO
Centos 5.6 i386 netInstall ISO

