Hi,
1st your question little bit confusing and can you explaned detailed??
you are creating ID for sql login(mixed mode) or windows login??
windows login---you need to created in Active Directory (as you know already I think)
Mixed mode---(sql login you need to create ID and pwd(the PWd sholud be Upper case and lower case))
http://www.movabletype.org/documentation/mt5/advanced/creating-a-sql-server-database-2.html
you are getting any difficulties or please post the Error here.
I think ,It will help you.....
Thanks&Regards,
DBA
SQL server DBA