I use WSS 3.0
I want fields like Name, email etc Read-Only.
Is this possible?
Mike is right about the user information list, but the ability to make it read only is in the farm administrators hands too. Per web application, you can block the ability to Edit Personal User Information. This security right is in Central Administration, Application Management, User Permissions for Web Application. That may give you at least one option of locking it down.
There are no "user profiles" in WSS. The info you are referring to is the User Information List which unfortunately cannot be customized like that. Each site collection administrator is going to have the ability to make changes since it is site collection scoped content.