Although you are completely free to setup Myriad using any data locations that suit your situation, if you want some suggestions then:
On machines where Myriad will run from 'local' files, use a smaller boot partition (say 10 to 20Gb) and then format the remainder of the space as one big partition (the 'D' Drive) The same applies to network servers that will only be serving files to other Myriad workstations
Create a top level folder in this D Drive called Data, Myriad or PSquared (whichever takes your fancy!) and 'share' it using the same name - under XP and 2003, don't forget to change the Share Permissions to Read and Write, otherwise clients won't be able to access databases and the like properly.
On machines that are connecting to this computer over the network, you can either Map a Network drive to the share (we recommend the 'M' or 'P' Drive) or use it via UNC naming direct - i.e. \\Server\PSquared
For most situations, we would recommend mapping a network drive as this makes it easier for users to understand, i.e - 'I put it on the M drive' - but you run the risk of someone removing the connection and causing a few headaches. If you are doing it this way then it's worth writing a BAT file that runs from your startup group to remap the network drive should it get lost.
The advantage to the UNC method is that there is no drive mappings to get lost, but it does make it quite a bit harder to use when you want to browser for files etc.
Anyway - back to what we put in the folder:
Under this folder, create an Audiowall Folder, a Directory Folder, and a System Folder:
D:\PSquared
D:\PSquared\Audiowall
D:\PSquared\Directory
D:\PSquared\MyriadIf you are running Scoop or Nexus then we suggest:
D:\PSquared\Nexus
D:\PSquared\Scoop
The reason for these folder names are that these are the ones that the new Setup Wizard looks for when it's checking for an existing data store.
When setting up Myriad, 'point' the Audiowall locations at the Audiowall folder, the P Squared Contacts Directory at the Directory folder, and the Myriad System Data Location at the System Folder.