Re: White Space Removal ~ SBS2008/Ex2007
Given that storage is cheap, leaving the content in Exchange is the best option. It will use less space that way and is available to the users easily. You have no limits on Exchange 2007 (well 8tb).
If you do need to retain the data then look at something like GFI Mail Archiver. However that will still require storage etc, because it uses a database – SQL usually, which will need licencing.