Per a question in this week's 2780 class, here's a quick reference for SQL Server product support lifetimes:

-SQL Server 2000 SP4 mainstream support ends April 8 2008. Extended support continues till 4/9/2013

-SQL Server 2005 SP1 mainstream support ends April 8 2008.

What does this mean? You can find a more detailed explanation here, and an excerpt follows:

Mainstream Support

Mainstream Support is the first phase of the product support lifecycle.

At the supported service pack level, Mainstream Support includes:

-Incident support (no-charge incident support, paid incident support, support charged on an hourly basis, support for warranty claims)

-Security update support

-The ability to request non-security hotfixes

Extended Support

The Extended Support phase follows Mainstream Support for Business and Developer products.

At the supported service pack level, Extended Support includes:

-Paid support

-Security update support at no additional cost

-Non-security related hotfix support requires a separate Extended Hotfix Support Agreement to be purchased (per-fix fees also apply)