Replacing a file server, will links break?

Here are the assumptions I am making for the answer I will provide at the end.

Assumptions:

1. Your Windows 2003 Server is a member of an Active Directory Domain
2. Your new Windows 2008 R2 Server will be a member of the same Active Directory Domain
3. You will be doing the "swap" during off hours when you can ensure no one is connecting to the servers
4. You will assign the exact same IP Address to the new Server
5. You will recreate all the shares with the exact same share names are before

Answer:

Replacing the old 2003 server with a 2008 R2 server using the same name and then attaching the data disk will work without breaking any mapped drives.

As long as the permissions are the same, you share out the same folders, and you're using identical computer names, this should be fine.

It's worth noting that this is a huge reason why I tell everyone to use DFS Namespaces no matter what size they are. It makes migrations a breeze, even in single-fileserver scenarios. If I were you, I'd consider setting them up as part of this project and slowly migrating to mappings with the namespace instead of the explicit server names.