whose process are using my database?

Where can i see all the active connections that attached to a particular database? I always get permission error when i tried to restore a backup db. It said i can’t restore becos the database is currently in used. What i normally do is stopped SQL Server 7.0 then restart again so that i can get rid of all the connections, but this include all the other connections that attached to other database (in the same SQL Server). Can i only disconnect those connections which affect my database without disturbing the others? If yes, how?