Hello Nancy,
We will be more than happy to help you with this. Please send an email to
dedicated@lunarpages.com if you haven't done already and our admins will assist you with OS upgrade. As you mentioned Centos 5 would require a clean install and either we reformat your current server and install a fresh Centos 5 on it ( this will require you have a backup of your domains) or we will prepare a new machine and migrate your account over. Our admins will assist you with any of the option you choose.
Thank you.
Vlad Panainte
Lunarpages System Administrator