Here is a simple function to find out the reserved drive letters:
#requires -Version 3 function Get-DriveLetter { (Get-WmiObject -Class Win32_LogicalDisk).DeviceID }
To list all drive letters in use, try this:
PS> Get-DriveLetter C: D: Y: Z: PS>
To find out whether a given drive letter is reserved, you could use it like this:
PS> $letters = Get-DriveLetter PS> $letters -contains 'c:' True PS> $letters -contains 'f:' False PS>