$freemem = Get-WmiObject -Class Win32_OperatingSystem

# Display free memory on PC/Server
"Computername : {0}" -f $freemem.csname
"Free Memory  : {0} MB ({1} GB)" -f ([math]::round($freemem.FreePhysicalMemory / 1024, 2)), ([math]::round(($freemem.FreePhysicalMemory / 1024 / 1024), 2))