If I install Replication components on SQL Server 2005 is in use, will this stop the service and sql server? This server is in use continuously and I can not down it for a moment but I have to install extra components too.
Muhammad --> I am fairly certain this installation will require either services to be stopped or a reboot as most feature changes/etc. with SQL Server end up requiring. You will have to find a downtime window, most likely.
Your safest bet would be to verify this on a non-production environment and see for yourself if that environment mirrors production as far as setup/etc.