Sharepoint 200 provides a record management feature which enables you to archive and route your data to the different site collection known as "Records Center" , however this feature is used to archive records(list items, documents and all kind of records in sharepoint) and not the entire site collection or sites.
You can also have a look at the third party options such as "DocAve Archiver".They have this product for Sharepoint 2010, however i am not sure about 2007