[PHP] PHP5+ to Excel engine/converter

Hey guys,

For a client of mine I need an php-to-excel convert. As with PDF converters, there is much discussion about which one to get and to be honest, I have yet to find a decent, trustworthy one.

So the question remains; does anyone know of a decent PHP5+ to Excel converter, with the ability to create multiple worksheets inside the exported excel. .xls files are prefered, .xlsx is fine too.

Thanks a bunch!