I would like to install it on a embedded operator interface that runs on Windows CE 7. I have downloaded the msi of Node.js but I am not able to install it on the emebedded device that run s on Windows CE 7
I think you can not install the msi, because it is not compiled for Windows CE. You may have to compile it from sources with --dest-os for destination OS or --dest-cpu for your cpu. Then it may work.
http://events.linuxfoundation.org/sites/events/files/slides/nodejs-presentation_0.pdf [Page 11]
As fuubah said Windows CE is not binary compatible with Win32 platforms (Windows XP,7,8 etc.) neither with the new WinRT platform. You'll need to rebuild it from the sources. I never heard about a Windows CE porting of node.js, but it's worth searching a bit around. If you find no porting, a Windows version that is build using Visual Studio 2008 would be the best starting point (Windows CE 7 can't run code built with Visual Studio 2012-13, for that you need Windows Embedded Compact 2013). The API are similar but you may need to re-implement something to work around the differences.