Always check out the original article at http://www.oraclequirks.com for latest comments, fixes and updates.
If you install Oracle 126.96.36.199 on a Windows x64 platform, a prehistoric version of SQL Developer is also installed in ORACLE_HOME\sqldeveloper, but, according to the release notes, it's unsupported or, better said, there are a couple of bugs that prevent you from running it off-the-shelves.
Being SQL Developer's version so old, it's probably a better idea to replace it with a newer one anyway.
To make a long story short, i downloaded the latest release of SQLDeveloper (2.1.1) and i replaced the contents of the original folder under the ORACLE_HOME with the files extracted from the archive.
Thereafter i also downloaded the JDK from Sun, err... Oracle, whatever, the executable installer named:
jdk-6u18-windows-x64.exe and ran it.
As a last step, when launching sqldeveloper for the first time, located in
i entered the path to java.exe of the newly installed JDK, located in
and i finally got SQL Developer working normally on this Windows x64 virtual machine.
In the end, considering the size of the downloads and Internet Explorer "friendly" security settings that suggested me to download Firefox not 10 minutes later, it took me more or less two hours to get SQL developer up and running.