Time for a little software upgrade, I have upgraded sandman.toonarmy.mine.nu (server that powers this site) to use PHP5.1 and MySQL 5 which have all been installed with no problems. Rather than compiling from source I used the packages available from dotdeb.org.
eAccelerator was the only problem it needed to be recompiled, but was not compatible with the changes to the Zend engine. After a bit of googling I found a snapshot that compiled fine with PHP 5.1. 