I have an XP pro system with SP1 (MSJVM was there).
I was upgrading to SUN JVM.
I uninstalled the MSJVM using the "unmsjvm.exe" tool that MS had released for a while.
I installed the Sun JVM j2re-1.4.2_05.
It all looks fine in Java console.
However, My applets simply don't load after these changes.
I never had problems with the sun jvm on other XP SP1a systems so Im thinking it had to do with removing the MS jvm.
IE is enabled in the java console,
Sun Java is enabled in IE|tools|ie options|advanced