I've attempted to use Linux as my "main" operating system in the past year, Ubuntu 6 to be exact. I also run a very old installation of Fedora on my webserver (which is down until I finish unpacking from my move). I'm sorry to say this, but Linux is a huge pain in the ass, and I doubt I will ever try it again for normal everyday use.
Game_boy, most of what you've said about Linux is true, except for the "easy to use" part. Like twesterm, I've programmed in linux, and I'm sorry to say that it's just a tremendous pain to get everything working the way you want it. Tons of customization features are nice, but not when half of them don't work right.
Also, a lot of "advantages" really aren't advantageous.
Linux is no faster than a proper Windows installation without all the crapware that OEMs preload computers with. If you buy a computer from HP, you can uninstall all the crapware and have a blazing fast computer.
Windows is a lot cheaper than you think. The retail price tag may be $200, but OEMs pay much, MUCH less to install it on your computer. Additionally, they actually get kickbacks from all the crapware they install (which is free for you to uninstall), essentially subsidizing the cost of your computer. The vast majority of PC owners buy OEM computers, which are no more expensive with Windows installed than with Linux.
99% of viruses and spyware are caused through user error. Someone opens an attachment, clicks a bad link in a phishing e-mail or IM conversation with someone they don't know, downloads what they think is a no-CD crack for the latest game, etc. Don't do these things, and you will be just as virus-free in Windows as you would be in Linux. I have owned my own PC since 1999, I have never installed antivirus software, and I have never been infected with viruses or spyware.
Stability issues plagued Windows 95, 98, and ME, but not NT, 2000, XP, or Vista. The release of XP and the end of the 9X line pretty much put an end to stability problems. The only thing that can crash Windows now are buggy drivers.
Linux zealots, Mac zealots, Firefox zealots, whatever kind of zealots are out there are all the same. It's all hype hype hype, and they can never get it through their heads that not everyone is exactly like them. The condescending attitude of these zealots is what really pisses me off. BlueVette, you give a really great example of this: "Hey, it's totally cool if you don't want to expand your computer with Linux." What a line, you sound like a used car salesman.
And money is not the only issue for people. Asking people to install a new OS is asking a lot! Most people would have to repartition their hard drive, and unless you're equipped with something like Partition Magic, that requires reinstalling Windows and all your Windows apps on a newer, smaller partition, and then installing Linux on another partition. It takes hours of use to acclimate yourself to a new OS. They have entire semester-long college courses on how to find your way around in a UNIX environment. People just don't have that kind of time.