If your freshly installed Tomcat 6.0 on Windows is failing to start with a mysterious error about javajni.c, it's because a Tomcat native library depends on msvcr71.dll file which is often missing on Win32 servers. Get a copy from another (likely developer) machine and drop it into SYSTEM32 directory. Tomcat 6.0 should now start like this blog's server just did. ;-p
BTW, following server.xml entry is what you need to enable NIO HTTP 1.1 connector for Cometd and other uses.
<Connector port="8080" protocol="org.apache.coyote.http11.Http11NioProtocol" maxThreads="150" connectionTimeout="20000" redirectPort="8443" />