Judging from the documentation on Win32::Ole:

The LastError() class method returns the last recorded OLE error.

and:

The last OLE error is automatically reset by a successful OLE call.

I'd say that LastError returns a true value if there was an error. If that is true, you can write:

if (Win32::OLE->LastError()) {
  print "Virtual directory was not created ($!).\n";
} else {
  print "Virtual directory created successfully.\n";
}
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I might be wrong, because I've never used Win32::Ole, but if I am, I'm sure somebody will correct me.