Convert all RTFs from a folder to DOCX using MS Word

rtfs2docx.ps1

$folder = "."
$word   = New-Object -ComObject Word.Application
$word.Visible = $false

# 6 = wdFormatXMLDocument (DOCX)
$saveFormat = 12  

Get-ChildItem -Path $folder -Filter *.rtf | ForEach-Object {
    $rtfPath  = $_.FullName
    $docxPath = [System.IO.Path]::ChangeExtension($rtfPath, ".docx")

    $doc = $word.Documents.Open($rtfPath, $false, $true)
    $doc.SaveAs([ref]$docxPath, [ref]$saveFormat)
    $doc.Close()
}

$word.Quit()