For desktop based applications, what are best practices to perform auto updates? Currently, we download all files, then copy and register (if com dll) to their respective directories.

I looked at Google Chrome update method. It seems that it first downloads a zipped file into a directory, and then unzips all the files. Also, they have a setup application which seems to be used to do the update. Additionally, they create a directory mapped to update version like 1.0.154.43, but they keep the old version's directory.