You need to backup the solution files not to backup the databases, so that you have the solution in a 2005 format as once you have upgraded them you cannot downgrade, its to ensure that you still have the originals.

RSScriptor is used to pull the RDL files from the reporting server, you then create a new solution in BIDS and then add in the RDL files which RSScriptior has saved for you in the location you told it to save them.

I have attached a copy of the tool.