<p>I would like to upgrade my web projects on an IIS 5 server from .NET 2.0 to .NET 3.5.  These web applications live on a server with other web applications that will not be upgraded to .NET 3.5.  The server administrator is reluctant to install .NET 3.5 because he is afraid it will break the applications on that machine that are running 2.0 and 1.1.</p>

<p>As far as I know this WON'T be a problem since .NET 3.5 is an addition to 2.0 more than it is a new Framework.  I would like the communities help gathering evidence to show him that their concerns are moot and it won't hurt the other applications.</p>

<p>Thanks in advance.</p>

It won't have any problem and you will be able to run your 2.0 and 3.5 application using the same server. This is because the code base for both of the frameworks is the same.