I use Windows 2000 Pro, IE6,Microsoft Beta2 antispyware, and Norton AV 2006.
The Norton 2006 has caught all the viruses so far, including Winfix, and I have had no problems. It costs about £25 from Amazon. I keep up-to-date with all the updates from Norton and Microsoft, which are free, and find it all very effective in keeping my computer virus, spyware and worm free.
It also works with MS XP.
Norton 2006 does not work with ME, Win 98 or 98Se.
I know many people slag off MS software including IE6, but if you use them with Norton 2006 and keep up the automatic updates then it all works well.