Hi Scott,
Can I take you up on your kind offer of source code for this product:
http://valums-file-uploader.github.io/file-uploader/
I assume (and hope :-) you mean your have the .Net/C# server side code. As there's only PHP, Java, CGI in the download.
It does look good though, allows updates with parameters and a complete event, just what I want.
Best Regards
Steve