How To Setup Exchange 2007, OWA, Multiple Domains

I need to setup a single Exchange 2007 server with 2 email domains abc.com and def.com. I required access to abc.com through Outlook 2003/2007 and OWA. I need access to def.com via OWA only. I require completely separate email, calendars and tasks for each domain.

I have tried to do this with various topics on the web to little or no success.

Any assistance will be greatly appreciated.