The original Sun Java 2 is available in the ‘non-free’ section of the Debian repositories. To enable this section first add the non-free repository to the apt sources file – the /etc/apt/sources.list should look like, – important parts are in bold:
deb http://ftp.us.debian.org/debian/ etch main contrib non-free

Now, update apt:
sudo apt-get update

Then install the Java debian packages.
sudo apt-get install sun-java5-jre