Asking for credential every time

Every Time that i connect is asking for credential, i'm using 3.5 and the database is SQL2000, the SO of my machine is Vista, the sql client is "Microsoft SQL Server Management Studio" is the one that come with SQL2005.

it doesn't store my credential.

1. You need to register SQL Assistant add-on for SSMS (please see documentation for details)
2. Start SSMS as an administrator (please don't assume that when are logged in as an admin and you double-click SSMS icon, it starts in admin mode, Vista doesn't work that way), you need to right-click on the icon as chose Run As Administrator. In that case SQL Assistant will be able to share connections with SSMS and you won't see connection prompts appearing on the screen.

But this about run the SSMS as Administrator it will be just one time, or every time that i start it.

Yes, in version 3.5 you need to start SSMS it as an admin every time, otherwise Vista will not allow SQL Assistant to access correct files and registry settings (this is all transparent to SQL Assistant and caused by Vista design, that doesn't happen on XP, Win2003 and other systems).

The only way to avoid it using admin mode is to upgrade to SQL Assistant v4.5 and use the Auto-Connect feature available in that version.