I think, the automatical updating of your applications
on user's PC is good idea. Also, sometimes you do not
want to add some big files in your installation
projects. For example you need to install the MDAC
(Microsoft Data Access Components) before using a MS
Access databases in your applications. But the MDAC
installation program is very big (about 7.5 Mb) and is
no necessity to install it on the Windows XP. You can
use IOUpdate.dll for it.

The IOUpdate.dll uses Microsoft's Component Object
Model (COM) technology to provide access to updating
services such as:

Comparing a current version of your application with
newest updates on your FTP and ask user for updating.
Return to previous version in any time if user wants
it.
Downloading and installing additional files or
utilitys from your application.

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