I downloaded knime 64 bit with eclipse etc. (archive) on my Windows 7 computer extracted and used to develop new nodes. No problem.
On my windows 8.1 PC node development is not possible since for some reason the required bundles are unkown to Eclipse (e.g.: org.eclipse.core.runtime, org.knime.workbench.core, org.knime.workbench.repository, org.knime.base).
I am doing nothing different so I am not sure how to tackle this problem.