XP SP2 and web sites

Fine-Tune Your Web Site for Windows XP Service Pack 2.  Make your Web site work well with the new security features in Windows XP SP2 that affect ActiveX controls, file downloads, pop-up windows, and more. [via MSDN Just Published]

I should think it is getting near to it being a requirement that your site plays well with SP2 and hopefully these documents are describing final functionality.