When you (or the one that installed SQL Server 2008) forgot to add an administrator, it is still possible to add one.
The How do you add an administrator user to SQL Server 2008 question on Server Fault pointed me to the right page SQL Server 2008: Forgot to add an Administrator account? by Chris Randall.
Note that you might want to run SQL Server in Single User Mode; the first answer on the above question doesn’t mention that, but the second does (and pointed me to Chris Randall’s page).
–jeroen
via: How do you add an administrator user to SQL Server 2008? – Server Fault.
