Auto Update / Install Feature for Visual C# 2010 app and .PHP file

We have an client based application built in Visual C# 2010. Periodically this .exe file automatically accesses a php file we have on our server. We want to provide our users with an auto install feature. It should automatically install a new .exe (software product) on our end user's machine. Completely silently and automatically. Two versions we want: 1) For existing users --- We need php code added to our existing php file to install a new .exe. Including error checking, accounting for UAC limitation, .etc. Anything that might prevent an auto silent install or cause our php file or .exe to "bomb". So, very basic php coding. 2) For new users --- We want a similar functionality built into our Visual C# 2010 code, but with more features. Being that we feel what can done in a php script file is much more limited than what can be done within the actual Visual C# 2010 code of the application itself. I'm thinking incorporate a .xml file on our server. The .exe file can periodically check that file (this functionality is already written in). Then based on content of .xml file, it can determine whether or not to install new .exe, name and location of new .exe to download and install, .etc. Again, same error checking, UAC limitation overriding, .etc So, Visual C# 2010 coding. Again, two projects. One for the existing users who need to be updated via our php file. The other, a feature added to our Visual C# 2010 app code that I can then compile and distribute to new users. Please let me know if you would like to bid on one (or both) of these projects. Please also provide a general overview of how you would accomplish this, as well as any prior experience for a similar project(s).