Same here. I made the transition when Microsoft made Genuine Advantage compulsory. My Windows was genuine (it came preinstalled on the laptop) but I thought, no way I am going to let Microsoft spy on me.

Like sulu, I made a dual-boot install with Windows secondary, to use when needed. It turned out I needed it about once a year, and that was only for things like sharing a screen over Skype (I must say, Skype on Linux is still a bit of a hit and miss: no SMS support, no screen sharing and, depending on your hardware and Linux version, you might need to hunt for an older version to make it work at all).

The only things I miss on Linux are
1. A simple picture editor like e.g. Microsoft Paint. GIMP is nice but too heavy for most use cases.
2. A good video editor. I've tried everything that Debian and Ubuntu had to offer. Most of them crashed on start. Those that worked had such a horrible UI that I ditched them.
3. A good DVD authoring software. See #2, the same applies. I found one that worked in Debian 6 but stopped working in 7 due to f**ked up dependencies. D'oh!

Everything else works just as good or better.