How to sync more than one iPhone on same computer?

Question

I have multiple iphones under my family plan as well as iPad2.   I use one iMac mainly for my business & to update my iphone 4s, and the older intel imac  to update the other devices. 
When we try to update/sync we get info from the last person who synced their iphone which is info that the other person may not want. 
How does one set up two different 24" Imacs running Lion so that each person's iphone etc. is recognized and contains just their info when opening/syncing to iTunes. 
I think I read somewhere that each person needs their own apple ID no./account? 
If so, how does having each of us with their own account ID work if we all use the same computer?   
Do we need to set up separate individual user accounts and when that person wants to sync to itunes they would log out of which account the computer is and log onto their own account before trying to sync to itunes?
Thanks
Bob

Answer 1

It's easier if each person has their own AppleID, that way when the connect they can login to iTunes as their Apple ID and their apps, music, etc.. will sync. The only other way I know how of doing it is create user accounts for each of the people logging into the computer and then they will be forced to used their own AppleID's. To create accounts for each person go to System Preferences - Users & Groups and add users by clicking the + at the bottom of the column.
BTW PLEASE complete your profile. We have a tough time helping if we don't even know what version of OS X you're running and what iMac you have. You can easily do this by clicking Your Stuff in the upper right then click Profile and add the pertinent information.