Microsoft have released SP2 for SQL server and express additions. This is the version that fixes some compatability issues running on Vista, as well as includes a whole host of new goodies.
As well as the traditional host of fixes, the new service park offers compression for some data warehousing applications, and other performance boosts. Theres a number of improvements in management for DB administrators and a new database wizard for better reporting.
Installing SP2 is straight forward, after agreeing to the UAC prompt and the licence agreement, you are presented with a list of which components you already have installed. Click Next a few times and it happens without any fuss.
You can download SP2 for SQL Server from here, or for SQL Express from here.