Been using various versions of Linux for oh, six or seven years or so now, starting with Red Hat back before they split it into Fedora and Enterprise. I've tried numerous other distros since then, including the Debian based install of Knoppix; SimplyMEPIS (originally Debian based, now Ubuntu based); Puppy Linux (a minimalist version that can run entirely in RAM if there's at least 128 Megs), and several other LiveCD versions (distributions that can be loaded and run entirely from a CD ROM, without the need for any hard disk alterations).
I've been running Kubuntu (Ubuntu with the KDE desktop, rather than Ubuntu's GNOME, which I don't care for) now through three major releases, and while I do occasionally bork my system (I like to fiddle under the hood sometimes), and major upgrades are sometimes a bit of a pain because I have to redo any customizations I've made in the interim, it has always been a rock solid distro with generally fewer issues with things like cranky hardware, and greater overall user-friendliness (IMO anyway) than just about any other Linux I've tried. Only thing I haven't tried using yet is my LightScribe DVD burner to actually do a label, since the specialized media needed still costs more than I'm willing to spend, but it works for burning the DVDs and CDs just fine.
I recently purchased a 'recycled' Pentium 4 based Compaq Presario 5000 for my wife; cost me $75, tower only (I had an extra monitor, keyboard and mouse). Came loaded with PCLinuxOS, which so far looks pretty smart and VERY user-friendly (it needs to be for her); been contemplating installing it on my machine, tho' I've been a bit reluctant as I believe it's based off of Mandriva, formerly Mandrake, and when I tried Mandrake out some years back I was not particularly impressed.
In all this time and through all these different flavors of Linux, not once have any of my machines ever been compromised, nor have I ever had to run (or even install) a virus scanner. Of course it also helps that my home network is fronted by a Linksys router with a custom Linux-based firmware named OpenWrt that includes firewalling.
Bottom line? Ditch Winbloze if at all possible and learn how to do more with your computer than 'point & click'. That's the best 'anti-virus' you can get.
(Incidentally, I heard from a tech at the computer recycle shop that Vista is the last OS for consumer home use that Micro$oft will be doing, and that they're supposedly going to be moving strictly into SERVERS. Isn't that just great? Now we're going to have their 'wonderful' software running the internet - which so far has been primarily *nix-based. I can hardly wait...

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"It means buckle your seatbelt, Dorothy, because Kansas? Is goin' bye-bye... "