I tried the JDK 6.0 release .. Mustang beta, but it made Runescape (a java game) mega-unstable.
http://download.java.net/jdk6/binaries/ - if you want to risk it... no way to just download the runtime, you have to download and instal the full JDK
I found some graphical flags to use - they can be set in Java control panel
-Dsun.java2d.d3d=true (flag to enable D3D rendering in JDK6.0 early access)
-Dsun.java2d.opengl=True (flag to enable openGL pipeline, all versions - severe colour errors result)
NB. uppercase T on True reports if the pipeline is enabled, lowercase t is silent
-Dsun.java2d.ddscale=true (flag to enable directdraw hardware scaling - all versions
unless OGL pipeline selected)
The first one only works with the 6.0 release
the second one is available in both, but it appears to cause a R-G or R-B colour component swap (ATI graphics)
The 3rd one, I'm using, I think it cuts CPU usage in some areas.