I agree with some of the other reviews. The book is now out of date with regards to current technology which is only to be expected really considering the pace at which things advance. Its easy enough to use it as a reference guide and simply adjust your needs to use more updated components and software. The thing this book will give you if you have never built your own computer is the confidence to do so. It illustrates how simple slotting everything together actually is.
The problem I have with it is that I find it a bit condescending, and at times the authors contradict themselves. They also reference very ordinary components, and there is no real advice on things such as checking the HCL list (hardware compatibility list) for Windows or where to find some of the high-end bits you might want to use. This isn't usually a problem as long as you ensure that the components you purchase have the "Compatible With Windows 7" logo on the box. Avoid using Vista unless you really have to as it is an absolute disaster of an Operating System!
So yes, its fine for building a fairly standard PC but I strongly recommend that you do additional research before starting your project. If you want a fairly high performance rig then learn what the jargon means and how it fits together with the components. This is especially important if you are using second-hand bits for some of the build.
They do give good advice on the various pitfalls such as ensuring everything fits into the case you choose, but then completely miss out on things like the software needed to burn or view DVD's in XP and Vista which will add to the overall cost (and for a first time builder may cause a lot of confusion/frustration when you can't watch a DVD in Windows Media Player for example).
I also advise anyone to research the additional software and drivers for the components you choose to ensure they don't cause conflicts and crashes for your particular hardware setup. Roxio software (often used for DVD related things) is famous for causing problems, although if installing Windows 7 this is not relevant.
Don't let this put you off though as its a useful reference, and if you take the time to dig a bit deeper you really can build a great machine. It won't necessarily cost much less than something from Dell or PC World, but it will be free from all the Bloatware that traditionally come bundled with store bought PC's.
Have fun building!