So the GUI tutorial that I found uses NetBeans IDE instead of Eclipse. I installed Eclipse a few days earlier because well, it's popular. Although with hindsight, I probably should have done more research especially after running through Eclipse's not-up-to-date java tutorial. It's probably not a big deal if my wireless internet connection is not downloading stuff at 10 kilobytes/second, yeap that's about twice as fast as 56kbps dial-up connection. Unfortunately I'm forced to use the frequently disconnected wireless before my router arrives.
Anyway, after some Googling and exploring around, I found out that NetBeans is actually the better IDE for implementing GUI in java. I proceeded to download and installed it(which wasn't done until this morning because of the slow download speed). And yes, NetBeans GUI builder is so good I wish I have such a good builder when I was coding my MEng project. The drag and drop visual builder would have made my life easier and made my project looks prettier. I wasted so much time painstakingly aligning the various elements. Netbeans solved all that by having a grid that you can snap your elements to at a distance(from other elements) that makes it looks appealing.
Update: Here's how my Sudoku solver interface looks like in the Netbeans IDE(there are a few more buttons at the bottom but it's not shown). To the right is the palette containing all the elements that you can drag and drop to create your GUI. You can also switch back to the source code to see how each element is coded.
Bottomline: If you are a beginner at Java or are new to GUI, then NetBeans is definitely the preferred IDE.