The migration process usually is done from WSS to MOSS, but once in a while there is the need to do the opposite, so what should you do?
First of all you need to be careful with the features of MOSS that don’t exist in WSS, so a good option is to deactivate them before trying to do a Backup or Export.
This can result in problems with your site, so the best thing is to insure that everything works with the MOSS features deactivated, before migrating to WSS.
Follow Nanddeep Nachan post on this.