Depends on how much separation you want.
Most users keep all their data separate by creating different Outlook
Profiles.
http://www.slipstick.com/outlook/olshare1.htm

Signature
Russ Valentine
[MVP-Outlook]
> My wife and I share one PC and we have different contacts that we wish to
> maintain. How do we create two or more contacts folders? Ideally we
> would
> have one for her one for me and then a joint name/address folder.