Powershell - how to replace OS Version number with String

I am querying remote servers for their operating system. I know that I can return the Version, but I want to replace these values with the friendly name. The code I have so far is:

$Computer = (gc c:\servers.txt)
$BuildVersion = Get-WmiObject -Class Win32_OperatingSystem -Property Version, CSName -ComputerName $Computer -ErrorAction SilentlyContinue
$Build=$BuildVersion.version
   If ({$BuildVersion.Version -match "5.2.3790"}) 
          {$Build="2003"}
   Elseif ({$BuildVersion.Version -match "6.1.7601"}) 
           {$Build="2008"}
   Elseif ({$BuildVersion.Version -like "6.3.9600"}) 
          {$Build="2012"} 

But this doesn't seem to work and only returns "2003" regardless. Please help, I'm fairly new to PS and coding.

thanks