I am new to alfresco and I am using alfresco community addition 5.0 for document management system.Upto now I don't have any problem.
now my doubt is how to move alfresco community from one system to another system without lose of data.
I would suggest you to look at the Backing up and restoring part of the Alfresco documentation.
To make it simple, you have data stored as three parts :
Of course, you should do your backup and transfert with your alfresco stopped, since database, contentstore and index are related.