There's two key data sets that you need to copy. 1) The Audiowall. This has all your .wav files plus 11 .lst files.
2) The Myriad System folder. Contains sub-folders such as COMMAND, SCHEDULE and LOGS.
Just copy both folders in their entirety. Standard Windows file copy is fine.
If you're using Myriad v3 then you will also need to copy the P Squared Directory folder and HKEY_LOCAL_MACHINE\SOFTWARE\PSquared\Myriad v3 key from the registry. You can use the regedit tool (type it in Start > Run) to export the Myriad v3 key to file that can be copied to the new machine and imported.
License wise, for v3, you will indeed need to re-license the new machine. However, you will need to release the license from the old machine first. This option is on the page of the license wizard that tells you what the current license code expiry is. Myriad v2's license is stored in the Myriad System folder and so should be copied across with everything else.
I would recommend that you download the latest version of Myriad rather than using the one on the CD. This will ensure that you get all the latest bug fixes and that your system will run as stably as possible. You can get this from http://support.psquared.net/products
Finally, you didn't mention AutoTrack but if you are using it then you will need to ensure that you copy that too.
If you're not sure about anything I've said here then give us a call or email support.