$size = @{Name="size(GB)";Expression={"{0:N1}" -f($_.size/1gb)}}
$free = @{Name="freespace(GB)";Expression={"{0:N1}" -f($_.freespace/1gb)}}
Get-WMIObject Win32_LogicalDisk -filter "DriveType=3" -computer (Get-Content servers.txt) |
Select SystemName,DeviceID,VolumeName,$size,$free | Export-CSV drivesizes.csv