TQuery asking user name and password always

Hi all!
I have a question that keeps me awake.
When I use a Tquery object against a MSSQL server, it keeps asking for the
user id and passwords screen before executing the query the first time.
Is there a way to supply the user Id and password automatically.
I have used a TDatabase object configured with the parameters USER NAME=sa
and PASSWORD= and  the loginprompt to false to no luck
Can anybody give me a hand?
Thanks in advance
Pedro Estrada