Windows 7: How to manage multiple users on same Outlook

At work, I have Outlook 2007 and four different e-mail accounts. Two of these are personal accounts that I don't want anyone else access and two of the accounts I need to let my colleague access.

So far both personal e-mail accounts need passwords to be entered before downloading new mail and two other public e-mail accounts have passwords saved on password list so my colleague can check new e-mails. My colleague can still go through my old personal e-mails, which is exactly what I don't want my colleague to do.

I have tried couple of different things and this is the latest:

(All different e-mail accounts have different .pst-file) I protected my personal .pst files with password. Great, does the trick, but now Outlook doesn't open because default folder has been protected with password and my colleague can't access the whole outlook. So it didn't work.

I changed one of the public ones to be the default folder and managed to get it working. If you don't enter passwords when requested for my two personal accounts, Outlook still starts and my colleague can access other two accounts. BUT, now all the incoming mail goes to the default account that is one of the public accounts! I made a filter or whatever it is called so that when one of my private e-mails is in the recipient field that e-mail gets moved to right folder. This works like a charm, except when my colleague is not "logged in" to my personal account, Outlook can't move the mail to right folder and it is displayed in one of the public folders.

And now I just noticed that if I don't enter the password the folder of each account I didn't enter the password changes to the default one which probably causes the problem.

I have wasted a lot of time with this and I really can't understand why this is so difficult or have I missed something. Some help and ideas please.

Thanks!