Outlook 2010TS and Outlook 2003 local issues

I have clients using terminal services and running Outlook 2010 in their TS profiles. Locally they run Outlook 2003 with both systems being fed by an Exchange server running in cached mode.

In TS the email works fine but as soon as they access their email locally they are getting error messages. I know there are compatibility issues between 2007 and 2003 but if the ost file is coming from an exchange server essentially 2003 is just displaying the information and not manipulating it beyond layouts.

Is there a solution to this that doesn't involve going out and upgrading all the local Outlooks to 2010?