How to sync outlook over vpn

I have an xp notebook at home and xp desktop at work. I use a vpn and Outlook 2003 to connect to my exchange server running exchange 2000 server. When i make changes and clean up my mail at home over vpn the changes do not occur at the workplace. I am using cached exchange mode. Please let me know why the changes do not sync and what to do about it.

Thank you so much