You can fairly easily install tomcat & Solr for Ubuntu via apt-get, but there are some quick caveats before you begin.  The packages are in the base repositories, but something is messed up with the dependencies, so you can’t just say “sudo apt-get install solr-tomcat5.5″ unless tomcat is already installed.  So, the right sequence is:

$ sudo apt-get install tomcat5.5
$ sudo apt-get install solr-tomcat5.5

I’m a bit nervous that solr doesn’t seem to work with (or rely on) newer versions of tomcat, but I’m to to stressed at the moment.  Once you’re done with the above, you can check your Solr install at http://localhost:8180/solr/admin

Solr config files live in /etc/solr/config/…