Do you actually SEE the window on/in the PSU? Unless you have one of those acrylic cases, or a really large window, you won't. Windows in cases are 100% flash and 0% function. Also, unless you pay for a high quality case, you'll have a louder system because of the window. Also since acrylic does nothing for heat transfer, or at least nithing good, your case won't run as cool as if you didn't have the window(s) installed.
The only real reason I can see for windows in anything, even a case, is for 100% show. That is, to showcase a system you're offering to build people. You can have it running while letting people see the internal components. Even then, most (well built) systems and cases, can have the side panels pulled of and run at least fairly well.
Oh, and for the Bubba that started this thread... Fix the topic summary... It's screwing up the rest of the thread views too...