Hi jsteltor,
Also, is there a way to force AJAX Uploader to use either the Silverlight or basic method?
Try this way, it will disable the flash mode.
attachment1.SetAdvancedOption(UploaderAdvancedOption.NoFlash, "true");
by default uploader will use Silverlight for upload. If user have not install silverlight, uploader will change to IFrmae mode automatically.
Regards,
Ken