Or just open a command line window and type 'whois <address>'.
Surely Windows has the whois command as well, doesn't it?
Microsoft Windows XP [Version 5.1.2600](C) Copyright 1985-2001 Microsoft Corp.C:\Documents and Settings\NAME>whois www.bbc.co.uk'whois' is not recognized as an internal or external command,operable program or batch file.