use Win32API::Registry 0.21 qw( :ALL );
my @software = qw ( Excel Word Outlook PowerPoint Perl );
for my $software (@software) {
    print RegOpenKeyEx( HKEY_LOCAL_MACHINE, "SOFTWARE\\Microsoft\\Office\\$software", 0, KEY_READ, $key ) ?
    "$software has registry key\n" :
    "$software seems to be missing ".regLastError()."\n";

}
__END__
Output on my system

Excel has registry key
Word has registry key
Outlook has registry key
PowerPoint has registry key
Perl seems to be missing The system cannot find the file specified