Unlike most security problems, this one is not limited to Windows systems. Macintosh and Linux systems are equally vulnerable.
You can read more about the problem in the BBC web site at http://news.bbc.co.uk/2/hi/technology/10257411.stm
Adobe is working to fix the problem. In the meantime, users of Reader, Acrobat and Flash should not use those programs. Avoiding PDF files (Reader and Acrobat) is rather easy. In fact, I wrote last year about other programs to replace Adobe Reader. You can find my Time to Get Rid of Adobe Reader? article at http://blog.eogn.com/eastmans_online_genealogy/2009/04/time-to-get-rid-of-adobe-reader.html
Avoiding Flash is a bit more difficult as it plays automatically when visiting many web sites. You can turn off Flash in most web browsers. You need to disable Flash in your browser's preferences. The exact instructions will vary from one browser to another.
I use Camino as a web browser on the Macintosh. To anyone using Camino: click on Camino and the click on PREFERENCES. Next, select WEB FEATURES and then check BLOCK FLASH ANIMATIONS.
Of course, this will block many things on web sites but that is preferable to having some stranger take over your computer.