Java Runtime

Sun has recently released new versions of Java Runtime because of a possible malware vulnerability in earlier versions. However, when I go the page to download the "fixed" version, I get confused.
I have never understood just what the difference is between
Java(TM) 2 Runtime Environment, Standard Edition 5.0 is
https://jsecom15c.sun.com/ECom/ECom...D;jsessionid=599101879F87C5616215F37C521FBD1D
and
Java(TM) 2 Runtime Environment, Standard Edition 1.4.2_06
https://jsecom16b.sun.com/ECom/ECom...3;jsessionid=011B6EFA908C0216C16B532563713723
and which is the fix.
I now have 1.4.2_05 (which apparently is vulnerable) on my PC. And sites requiring Java run just fine.
So which of the above do I install? Or is it both?

 

PeteC --Thanks!!
If you are willing and able ( ), what is the first one?