You want to convince him? Ask him to let you install it for your own use, leaving IE as the default browser. Then use it regularly in front of him. He'll see you using stuff that IE doesn't do, and eventually will start to use it himself. And if he doesn't, it doesn't matter.
I showed my dad how I can open news.google.com, use all in one gestures to open each news article I'm interested in reading in a background tab, and then click on the first one and start reading. Click close, second one is automatically brought forward. and so on. I showed him how all my favorites can be put into a bookmark folder and I can open all of my favorites at once.
After he saw that, he decided to start using firefox again. He had tried it before (when it was less stable) and wasn't happy with it. But now he's a firefox convert and regularly worships at the feet of the great mozilla.







