This plugin for the NSIS installer will invoke the .NET 2.0 Framework installer after it has been downloaded. It will do its best to make the installer run without user input, while giving the user feedback in the form of status bars and so on.
Steps to use:
What it does:
The DotNET.nsh macro checks for the presence or absence of the .NET 2.0 framework. If the framework is missing, it will download the file from MS and invoke the NsisDotNetInstaller plugin. The plugin invokes the installer in semi-silent mode, but unfortunately the installer will prompt the user to close the main installer before continuing with the framework installation.

The NSIS plugin will look for this window to appear while the installer is running. If it does, it looks for the 'Ignore' button and sends a BM_CLICK message to it.
Note that I haven't tested this on foreign language computers. The Cancel, Retry, Ignore text is hard coded so this trick is not likely to work, although the only difference will be that the user has to click the Ignore button on their own.
License
This plugin is licensed under the GNU GPL. If you make improvements,
please submit them or post them on the
NSIS web site. It is in the community's best interest for the .NET
framework to spread through the Earth!
Credits
The original DotNET.nsh macro was written by AnarkiNet.