Windows Server 2008 – How to Determine 32 or 64 Bit Version Installed

Or try this:

PS C:\Users\jeffh> $os=Get-WMIObject win32_operatingsystem
PS C:\Users\jeffh> $os.OSArchitecture
64-bit

Found at: http://msgoodies.blogspot.com/2008/05/is-this-powershell-session-32-bit-or-64.html

I believe only the ACPI HAL ships with Windows Server 2008. Mark Russinovich mentioned something about it when discussing the changes to the kernel. Geoff Chappell has some great history on the HALs.