If you only want to see tasks and NOT emails in your To-Do Bar, try this:

Show you To-Do bar
Right click on the Subject bar
Select Customize Current View
Select Filter
Select Advanced tab
From the Field drop down menu, select All Mail Fields/Email accounts
Add Condition doesnt contain and YOUR email address in the value field
Select Add to List and OK

This worked well for me with ONE email account. I could not get it to work with more than one account either by adding more than one account to the value my.email.com; my.otheremail.com or as two separate filters.

Everyones setup is usually different so you will just need to play with the filters.
You cannot edit a filter, you will need to delete then add.

Hope this helps.