use Win32::OLE;
use Win32::OLE::Const 'Microsoft Word';

my $dir = "C:";
my $ext = "wps";
my @files = map{ s!/!\\!g; $_ } grep{ m/\.($ext)/ } glob( "$dir/*" );

# check if Word exists and is running
my $word = Win32::OLE->GetActiveObject('Word.Application');
die "Word not Installed" if $@;

# start Word program instance if required or die if unable to
unless (defined $word) {
    $word = Win32::OLE->new('Word.Application', sub { $_[0]->Quit; } ) 
        or die 'Cannot start Word';
}

$word->{Visible} = 0;  # set to 1 to watch

for my $infile( @files ) {
    my $doc = $word->{Documents}->Open($infile) or
        die "Can't open $infile, Reason:$Win32::OLE::LastError";
    (my $outfile = $infile ) =~ s/\.\w+$/.doc/;  # change file extension to .doc
    $doc->SaveAs( { FileName => $outfile, FileFormat => wdFormatDocument } );
    $doc->Close;
    undef $doc;
}

$word->Close;
undef $word;