Try a build with jdk/jre 7 - it works great. j7 adds a lot of language improvements and actually fixes bugs in jre6 and lower. You should use it whenever possible.
I don’t have any experience working with sparkplug, but…
For building Spark, I can successfully build on a win7, winXP using Oracle j7 and Fedora (linux) box using OpenJDK 7 with no issues. For packaging, simply bundle your jre7 folder and rename to “jre”, then include it in your package build for something like Advanced Installer or similar.
I think if you see a requirement of j4 or something, you can more or less treat it as a “j4 minimum requirement”… Happy building!