<p>How can I find out which Service Pack is installed on my copy of SQL Server?</p>

From TechNet:
Determining which version and edition of SQL Server Database Engine is running
```
```
-- SQL Server 2000/2005
SELECT  SERVERPROPERTY('productversion'), SERVERPROPERTY ('productlevel'), SERVERPROPERTY ('edition')

-- SQL Server 6.5/7.0
SELECT @@VERSION
```
```