Java installation question

[Gerhard Magnus]

An application I need to run at a website requires that my browser
(Mozilla firefox) have the Java Runtime Environment (J2SE50).  The Sun
website offers these options:

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Linux Self-extracting File
This file can be used to install the Java platform in a location chosen
by the user. This file can be installed by anyone (not only root users),
and it can be installed in any location. It will not displace the system
version of the Java platform supplied by the Linux operating environment
(unless you intentionally install it in the same location as the
system's Java platform, which requires you to be root user).

Linux RPM in Self-extracting File
A Linux RPM package file to be installed with the rpm utility. The RPM
packages require root access to install, and they install by default in
a location such that they replace the system version of the Java
platform supplied by the Linux operating environment. 

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Which of these installations is recommended so that (1) Firefox can find
the Java plugin and (2) I don't damage any system version of Java that
may already be included in Fedora 3?