Auto update and data in writable folder

Some users don't have the ability to write into Program Files. Is there a better location that my application can auto update into and where i can have my application store data.

I need to have any user who gets onto the computer able to read and write to this location, so My Documents doesn't work well.

Is C:\Documents and Settings\All Users\Shared Documents an appropriate place for my auto updating the program and saving the data

We are using the NET Client Applications: .NET Application Updater Component from http://windowsforms.net/articles/appupdater.aspx

We're using Visual Studio 2003 and working in C#