My roommate's Dad, who worked for IBM for many years, has an older Aptiva desktop computer. He's been running Windows 98 SE for years and has had several spyware and adware infections despite my best efforts to keep him up and running. I installed and ran Ad-Aware, the McAfee suite, etc. etc. and still he had problems. He finally reached the point where he'd had enough and we started talking about either upgrading to Win XP or moving to Linux. I ordered a free Ubuntu Live CD for him to try.
It took several weeks, but when the Ubuntu CD arrived, he was very excited to try it out. After several days of playing with the Live CD, he decided he wanted to install it on his computer. I performed the install, of course. I was worried that Linux would not support all of his hardware (a Lexmark printer, a web cam, wireless card, and an HP scanner). Although we had some trouble with his wireless card (it was a Netgear USB MA111), after replacing it with a low-cost Linksys card everything is up and running. Even the scanner works.
Running so well, in fact, that I was able to get my iMac to print to his printer, something I couldn't do while he was running Windows because there was no Macintosh driver for his printer that would work with Win 98. But since we're both running a unix-like system (neither is pure unix, but both are so close it doesn't matter) we both use CUPS (the Common Unix Printing System) and can now share printers.
The long and short of it is that we've now become a Windows-free household.
I used RedHat Linux several years ago and though it was an OK OS for a tech-head like me, it wasn't "ready for prime-time." The average user just had to learn too much to make Linux a viable OS for most users. I'm happy to say, though, that the progress that's been made in the last 5 years has made Linux VERY usable and compatible.
I'm not going to say that there was NO tech knowledge needed, I did have to fight with the new wireless card to get it working, but the majority of the distro has been well-thought-out and I'm very impressed. I prefer the KDE desktop myself, but he seems happy with GNOME.
If I couldn't have a Mac, I'd use Linux myself. It's that good. And it's FREE. Yep, the OS and all the software are FREE. Can't beat the price!
If you're thinking of 'upgrading' to XP or Vista, give Linux a try first. It's secure, it's not prone to viruses, and there's lots of FREE software available for it.
I think it's pretty clear that Microsoft is losing its hold on the IT market. Unix, in all of its flavors, is the only true competition for Windows.
Trust me, you CAN live in a house with no Windows.