Before you decide you want to switch to Linux, ask yourself „Why do I want to switch?“
If the answer is „I want an OS that puts all the power in the hands of the user and expects him to know how to use it“: Get Linux. You’ll have to invest a substantial amount of time and effort before you get it to where you want it, but you’ll eventually be rewarded with a computer that works exactly the way you want it to.
BUT. . .
If the answer is „I want Windows without the problems“: Do a clean install of Windows XP SP2; set up a good firewall; install a good anti-virus; never use IE for browsing the web; update regularly; reboot after each software install; and read about good security practices. I myself have used Windows from 3.1 through 95, 98, NT, and XP, and I have never once had a virus, suffered from spyware, or been cracked. Windows can be a safe and stable OS, but it relies on you keeping it that way.
If the answer is „I want a replacement for Windows without the problems“: Buy an Apple Mac. I’ve heard wonderful things about the Tiger release of OS X, and they’ve got some lovely-looking hardware. It’ll cost you a new computer, but it’ll get you what you want.
In either case, don’t switch to Linux. You’ll be disappointed with both the software and the community. Linux is not Windows.