Exchange 2010 SP2 MRM 2.0 - Outlook 2003 SP3

Hi,
 
We are finishing the migration of Exchange 2003 to Exchange 2010 SP2. We are still running Outlook 2003 SP3 clients and would like to avoid going through and upgrade since we are testing VDI which will deploy WIN7 winth Outlook 2010, etc... and we are almost ready to get that going.

That being said, with Exchange 2003 we use to have a pretty tight retention policy for example we purche the users INBOX every 30 days. The retention of the email was changed when the email was flagged, opened to be reviewed or modified. The users used to do any of these actions to extend the life of the emails that they wanted to keep much longer time.
 
With MRM 2.0 I have seen that neither flaging, opening or modifying the email changes extends the life of the emai. The only way to acomplish this is by allowing the user to apply a different retention policy to the email.
 
Since I am still running Outlook 2003 SP3 I think that my users don't have access to apply new/different retention policies.
 
Some questions:
 
1. Is there any way to extend the life of an email by opening, flag or modifying it like we use to do with Exchange 2003?
 
2. If MRM is the only way to extend the life of the emails, for the time being can we use Outlook 2003 SP3 to manage the email retention in some way? I know that they can do WebApp but this is not an option.
 
Thank you ALL in advance for your help.