Hi Arthur,
I've always been a huge open source fan (I'm a software developer by trade and enjoy the freedom of open source).
But from a business point of view though the decision is much easier to make ... what is the best ROI. Free software is great but if it takes twice as long to get the same results you are much better off using commercial software.
Every year open source software is getting better ... let me know if there is anything in particular you are looking for.
Regards,
Ray Smith
RaymondSmith.com