Ok. I tried to live without Microsoft for two weeks now and I confess…I’ve failed miserably. Like everything in life, there was some good and some bad in not using Microsoft anymore. But personally, as much as Firefox worked really well and is much better than Internet Explorer, Thunderbird is no match for Outlook. The rest of Microsoft Office is marginally superior to Openoffice, with the not-so-negligible fact that Openoffice is free and Microsoft Office is really expensive. For one person, the hefty price of a licence is tolerable, but buying licences for a whole company or NGO? No, thanks.
Bottom line: You definitely gain some things living without Microsoft, but you certainly lose out on other things.