Originally Posted by brianhos
Apache 1 to Apache 2 is total cake if you are not using any of the advanced modules. Mysql 4 to 5 is pretty easy too. PHP on the other hand was a **** to get working for me.
Advanced modules like "SSL" or "virtual hosts". The configuration is significantly different between Apache 2 and 1 for those, and it's a major pain to migrate configuration files, in my experience. It would have been so nice just to start with Apache 2 from the get-go.