PHP 4 or PHP 5

[eluser]Elliot Haughin[/eluser]
Regarding IE6:
I wouldn't put it past IE6 to crash over any old thing... I'm sure they must have a line of code in their exe that says something like:

Code:

if ( page_is_too_stylish )
{
render_however_i_feel_like();
go_crazy();
dont_work();
cause_javascript_errors();
recite_poetry();
die();
}

On to more serious issues:
When using CodeIgniter, I always stick with PHP4. Because, that's what CI is written in. It makes sense to make your requirements for your extension match the requirements of the framework which runs it.

Don't get me wrong, I love PHP5... but if CI runs on 4.3.2+, then your whole application should too.