Switch from NTdomain back to Workgroup

I am currently looking over a small network of about 30 computers. They login into an NT Domain. It was not utilized to set elaborate permissions other than just to create user logins. I would like to change all pc's to use a workgroup instead.
How can I move the user accounts on the pc to workgroup but keep all of their information ie apps docs email etc..??

 

I haven't used it in a long time but this is what I used in the past.

http://www.forensit.com/products.html