Thanks everyone for your comments, I really do appreciate all of them.
So I just install SIMS on the new machine as I would a normal client machine, backup the existing database (assuming I'd be using DBAttach), copy the files and then restore the database and finally point everything in the right direction. Oh and copy of the extra files.
For some reason I was expecting this to be a much more difficult process.
Vikpaw, you're right it's for a primary school and we currently have one of the office PCs acting as the Server. I've just got used to using the staffs terminology.