I was perfectly happy with Windows (XP then) when I decided to check the greener grass on the other side of the fence (Red Hat, first, then Debian, then Ubuntu) and I never thought about going back. Linux is so much more refined under the hood that more than compensates for the lack of software in several niches. I recommended my then girlfriend (now wife) to buy a Mac when she wanted to upgrade her PC and she loves it. I wouldn't recommend Linux for her because the added elegance under the hood would not compensate the limitations in dealing with complex (read quirky) Office documents.
Now, we both cringe our teeth because our employers issued Windows running Dell laptops for us. Argh.