Well, I support many computers, and they run four different OSs. A couple are for my wife's business, another two are for my granddaughter. I've moved them over to TBird.
On browsers (not to get too far OT), I use Epiphany for most things. I'm just used to it, and it has all my bookmakrs, password and such. One internal site I use needs a few features that Firefox has, so I use that. I use FF/Wine for Flash. Linux-Opera I use sometimes; certain web sites (mainly a grant submission program) requires IE.
The same is true for text, BTW. I use five different programs for text processing, depending on the need. That's in addition to a couple of different text editors.
I guess I use a toolbox that has a lot of different hammers.