On Amazon, you can buy the two together at a special price. At Sun Microsystems Press, you can buy them at a 30% discount. The sunglasses you'll have to get yourself somewhere. Laptop too.
And for examples of how well the two books work together, see 82 New NetBeans Samples... Free! In short, if you combine the Swing tips and tricks of Chet and Romain's book with the richness of the NetBeans Platform, you can have extremely cool front-ends on top of a pure Swing framework that will give you all the plumbing and infrastructure you've always wanted, such as a complete out-of-the-box windowing system, plus a whole lot more. And here's a very concrete example of the result, showing the cool layered pane tricks from "Filthy Rich Clients" on top of an application based on the framework described in "Rich Client Programming":
Logically, the two books should go hand in hand very well. I'm really looking forward to reading "Filthy Rich Clients". You will find a review on the book here, in the next few weeks.
In other news. The best article I have yet read on the amazing improvements in the NetBeans Java editor is NetBeans 6.0: New Core Features in Depth, by Osvaldo Doederlein. If you haven't come across it yet, I highly recommend that you take a moment and read it, to really understand how revolutionary the 6.0 changes really are.