WebClient DownloadFileAsync File Exists

Is there a recommended method for using DownloadFileAsyc and determining if the file exists? It seems that the only way I can tell is on the DownloadCompleted event the error property has a 404 error in it, and the there's a开发者_如何学运维 file created that is 0 bytes.

It would be nice to have a more deterministic method.

---

Chris T had the right answer. (or at least good enough for me).