Active directory impact on local users

Dear friends,

We have a 30 systems with windows 7 professional here in the work group module. All the systems havetwo user accounts namely admin and staff,all of us employee will use the staff account. Now we planned to implement the domain concept here. I believe once we implement the domain, the objects(users) will create in DC itself. My doubt is what will happen to mystaff user profile in all the client machines. Am i need to delete that staff account before adding that machine to domain? Or it can be exist without any probs?

Thanks,

Lingaprakash R