I assume you have an ID which has admin privileges.

In SQL Server Management Studio, go to Security, then Logins.

Double click on the sa account to bring up the properties sheet.

On the general page, note the check boxes for Enforce password policy and Enforce password expiration. This is new for SQL 2005 - sa can be treated like a Domain User account for password complexity and expiration.

The Status page will allow you to unlock the account.

sa already has implied access, there shouldn't be a need to add it to any roles. sysadmin covers quite a bit.

Books Online would be good to look at. Quite a few changes in this version.

See if you can get by without re-enabling the sa account. It's generally not a good idea to use this account. And if policy did not disable the account, someone may have been trying to use it.

Hope this helps.

Greg E