Powershell script to determine OS architecture (32bit or 64bit)

This will return either "32" or "64" depending on the OS architecture.

Write-Host (Get-WmiObject -Class Win32_Processor | Select-Object AddressWidth).AddressWidth

NOTE: this is OS architecture, not CPU architecture. That is not relevant on 64bit machines, but if you have 32bit Windows running on a 64bit CPU it will return 32.