Its a bit more complex than that

Run DCPROMP on the second machine. Once Active Directory is installed then to make the new machine a global catalog server, go to Administrative Tools, Active Directory Sites and Services, Expand ,Sites, Default first site and Servers. Right click on the new server and select properties and tick the Global Catalog checkbox. (Global catalog is essential for logon as it needs to be queried to establish Universal Group Membership)

Install DNS on the new server. Assuming that you were using Active Directory Integrated DNS on the first Domain Controller, DNS will automatically replicate to the new domain controller along with Active Directory.

If you are using DHCP you should spread this across the domain controllers, In a simple single domain this is easiest done by Setting up DHCP on the second Domain controller and using a scope on the same network that does not overlap with the existing scope on the other Domain Controller. Dont forget to set the default gateway (router) and DNS Servers. Talking of which all the clients (and the domain controllers themselves) need to have their Preferred DNS server set to one domain controller, and the Alternate DNS to the other, that way if one of the DNS Servers fails, the clients will automatically use the other,

Both Domain Controllers by this point will have Active Directory, Global Catalog, DNS and DHCP.

Next move the FSMO roles to the new DC as described in http://www.petri.co.il/transferring_fsmo_roles.htm

You can now demote the Old DC by running DCPROMO on it to remove Active Directory.

Then repeat the process in reverse to move AD back to the re-installed server.