Also, in addition to what Bob said, consider switching to Mozilla as your browser. It will help you keep from being reinfested with spyware since most spyware is written to exploit the lax security measures in IE. Even if someone did target spyware at Mozilla users, you can't do "drive-by" installs like with IE. You have to click on a link to install something, AND a dialog box will pop up making sure you want to do this. It may seem like a bit of a hassle, but compare it to the hassle of dealing with spyware.
And if you ever decide you want to give Linux a shot, you can carry over all your settings to the Linux version of Mozilla, as well as having a familiar interface.
You've always got IE for those one or two rare pages that won't work in anything but IE, and Windows Update. It's completely free software, so all you've really got to lose is some time and effort.