We rolled our own as well. Its really not too difficult.
Our process goes something like:
When the main app is launched, it checks (using funcs from the synapse library) if there's an update available (assuming its configured to check, of course).
If so, it notifies the user and askes if they want to update.
If they do, it launches an updater .exe, and closes the main app.
The updater exe downloads the new files based on the contents of a text file it retrieves, keepiing the files in memory.
When the updater is done downloading everything correctly, it then saves the downloaded files to disk, backing up any files it replaces. This way if the download gets interupted, you dont end up with half the files installed.
Finally, it launches the main app again, and closes itself.
The trick w/ Vista is that you need to have an entry in the updater program's manifest to force it to run with administrator rights.
