Please note that the way how to install plugins differs from each version of Eclipse to the next one. The following description is for Eclipse 3.5. See http://subclipse.tigris.org/servlets/ProjectProcess?pageID=p4wYuA for more detailed information by the plugin provider.
http://subclipse.tigris.org/update_1.6.x
To verify that the integration works, try the following steps:
https://matsim.svn.sourceforge.net/svnroot/matsimmatsim/trunk.
While Subclipse includes everything it needs to run on Windows 32-bit, it has some additional dependencies on Linux and Mac OS X. Especially, Subclipse requires that you have the correct version of Subversion installed on your machine along some libraries to make Subversion usable by Subclipse. Please have a look at the detailed information provided directly by the Subclipse team. For Windows 7 64-bit, see these informations.