These days remaining Windows 2000 Professionals users are from corporate catagories who are using branded IBM, HP , DELL Pc's. As far as IE 7.0 & WMP 11.0 is concerned, those developer's dont need it. How ever day by day no softwares will support Windows 2000 professional edition.
We still running Windows Server 2000 in our organisation. We have Mixed mode domain. Windows 2003 servers also we have, Exchange 2003 as a mail server. Exchange is better than any other E-mail Server...
Many companies still using Windows 2000 professional edition on employee's laptops as it's 1 of the most stable OS from Microsoft with less patches and secured . Usually in corporate world employees dont need multimedia things, so I guess they'll upgrade to Windows XP when support,updates for Windows 2000 ends by Microsoft.