At work, I use Firefox, Audacity, and FreeMind, but still battle OSS objections, particularly when recommending software that would affect many users (*cough* Moodle).
From my perspective, I can’t see how Moodle has a less certain future than NameBrand LMS, which is part of a suite that was bought by another company, which has its own LMS and isn’t so interested in supporting NameBrand any more. Just sayin’.
At your company – or among your clients – has OSS reached a point where you can compare features without having to discuss open-source philosophy? Is OSS, in fact, preferred? At my company, the answers are no, but I’m optimistic — and hopefully rightly so.