You can find support life cycle information on the Microsoft Support web site at this address: http://support.microsoft.com/?pr=lifecycle
For SQL Server 7, mainstream support ends 2005-12-31, and extended support ends 2010-12-31.
For SQL Server 2000, mainstream support ends two years after the next version of the product is released (SQL Server 2005 was just released, so mainstream support for SQL Server 2000 will end 2007) and extended support ends five years after mainstream support is retired (2012.)
-- J.Kozloski, MCDBA, MCITP