.net autoupdater

I'm writing an autoupdater for a product or ours and really was just wondering if anyone had any idea's or considerations I should be aware of.

The product consists of the 2 .exe's, several .dll's, several report files, a local MSDE database on each users machine and a central SQL Server database.

As far as I can see there are only 3 possible types of update, replacement of a physical file, modification of local database and modification of central database. Is there anything obvious I've missed there?

So i will first need to check if any updates are available, if so download the updates and finally apply the updates.

If anyone has any recommendations on methods to check if an update is required and how to apply them I'll gladly listen.

Cheers.