Great topic!
I'm a Linux Administrator and there is no doubt, for servers, I would run Linux any day of the week. There is no comparison between the stability of Linux and Windows. We use SLES9 and the footprint of Linux systems in our data center continues to grow. I've noticed this year when sourcing software, most vendors have a Linux solution, so it makes it easy. The licensing alone saves a bundle when compared with access licenses to Microsoft OSes.
I've been running Linux at home for about 5 years. I wouldn't say I'm hard core, but I'm fairly knowledgeable. I've tried every distribution out there on all different kinds of hardware. I run Suse 10.1 on my work laptop because we run SLES9 on the servers. It's just easier to stay somewhat consistent. I can do pretty much everything on my laptop I need to. There are some limitations and it definitely isn't as easy to get things going like on a Windows system. I'm probably going to load SLES10 on my laptop just to be consistent, but I've been tempted to blow it away and try running Ubuntu for awhile. Suse really has problems with patch updates.
Simon, I think you are absolutely right. Linux was supposed to "take over the world" including the desktop years ago. The problem is caused by what makes Linux so great...free software. All these people maintain bits of software that are congealed into an operating system. Dependencies and patches can be a nightmare to solve for the casual user. In that way, the gap between Linux and Windows is widening. For the corporate desktop, switching to Linux is realistic. The first step at our company to make the change is switching 4000 desktops from Office to OpenOffice, which is in progress and is going well. It's going to save us a ton of money.
I almost bought an Intel Mac last year when I bought my laptop, but I backed out at the last second. There didn't seem to be a viable GPS program at the time and I needed my laptop for that.