Can I use a workflow to update a field with the value of another field? Or of the current date?

Can I use a workflow to update a field with the value of another field? Or of the current date?

It looks like I can only enter text for the field to be updated to. I need to update it to the value of another field.

The use case I am using is that I want to keep track of the lead's "Initial Interest Level". Whenever I create a new record, I simply copy the value of Interest Level (e.g. "Passive") over to Initial Interest Level. That way, when I change the Interest Level to "Active", I retain the knowledge that this lead started as "Passive".

Please advise!

Scott