i had the same problem with vista and win 7.
- just downloaded the latest sql developer 1.5.5 version WITHOUT jdk included
- exported my connections from the previously installed sql developer and
- deleted my installed version!
- then downloaded the JDK 1.6 update 16 from sun and installed it: http://java.sun.com/javase/downloads/index.jsp (32bit version! even if you have win x64. sql developer doesn't accept JDK x64!)
- then i unzipped the sql developer 1.5.5 i downloaded (without the jdk)
on first start sql developer asks you for the path to java jdk: given it the path that i installed the jdk 32bit from above and it now runs fine!
even without switching from aero to basic windows design and without redrawing-problems.
hope this helps you too...