This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Implementing runnable is the best way since you will get a chance to extend other class.
When you are working with AWT/Swing you must have to do this using runnable.
Otherwise it doesn't make much difference.