regarding the soon coming upgrade from debian 3.1 to 4.0

[Ovidiu]

hello,

I was jsut wondering what steps to take and how to prepare when 4.0 will be ready, I mean I know it will not be hard tu upgrade, something like apt-get update followed by apt-get dist-upgrade should just work but I was wondering on the implications of upgrading as there are some really big upgrades as I know about these upcoming new versions in 4.0:

PHP 5.2.0 and MySQL 5.0.30

so how can I make sure, not all my clients sites break when I do this upgrade?
are there any tests I can perform? can I somehow leave php 4.?? enabled too?

what is there to do?

btw. I initially used the debian 3.1 perfect setup from howtoforge.