[CentOS] Java RE

Hello.
Package Manager reports (with a green checkmark) that I have java-1.6.0 
installed on my machine (running Cent 5.3), but it seems to not be 
running. I used http://java.com/en/download/help/testvm.xml and got
"Something is wrong. Java is not working."

Perhaps I'm confused on which program I need to use java-coded apps. PM 
lists this app as "OpenJDK Runtime Environment" - is this it?

[mykolas at sr1220 ~]$ rpm -q jdk jre
package jdk is not installed
package jre is not installed

Can someone explain, or provide a link to a particular webpage that 
would clue me in?