you probably have tomcat installed with your distribution... assuming you are using redhat, mandrake or one of the other popular names. if not, you can download the .tar.gz file from the page you indicated above. which distro are you running?
If you have an RPM-based distro and tomcat didn't come installed, I recommend downloading the RPM version from jakarta.apache.org. Note that unlike the tarball (tar.gz) download, there are no sample apps pre-installed in the RPM version. Also the default port settings are different. Finally, the RPM places files in their "distributed" places rather than in a local directtory tree, so that for example, the server.xml file for Tomcat 4 would be found at /etc/tomcat4/conf/server.xml. That may seem more complicated, but it actually makes it easier to administer the system and I personally like it when all my config files can be backed up by making an archive of /etc instead of digging around all over the filesystem.
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