For the last few years, I have been a sys admin on Linux and Solaris servers. Like most people, I was running XP at home and was always perfectly happy with it. Recently my laptop had began to slow so I decided I'd take the plunge and install Ubuntu (Linux).
The first thing that really got me was how nice Ubuntu looks. On a 1.86Ghz CPU with 2GB RAM. I have gotten a very nice looking desktop. It also opens all programs much faster than Windows did and has a faster boot time.
As a sys admin, I had exposure to quite a few systems or tools that I use. Being able to run Squid as a local proxy is excellent, I've always felt Squid's ad blocking was better than any random ad blocking software. The open source community has gotten better too with Linux equivalents to nearly all the Windows programs I use.
The only places I have found trouble are with iTunes (iPod Touch) and my remote control (Logitech Harmony 1000). I've gotten round both of these by installing VirtualBox and running a virtual Windows in here. This took a bit of tweaking for USB communication but has worked since and I can sync my iPod with it now. I'd still prefer Apple and Logitech actually wrote a Linux version, after all Mac OS X is based on BSD. I still have my original Windows partition installed but could probably replace it, the fear still has me. From what I've seen, virtual Windows will do everything I need.
If you are considering taking the plunge and installing Ubuntu as your primary OS, I would strongly recommend it. VirtualBox is free for single use non-commercial machines and runs Windows perfectly, especially if you only need a couple of apps. Ubuntu is definitely more stable and looks a lot nicer. Oh and don't forget, free.