This book is NOT for everybody. But if you need to extract maximum performance from Windows 95/98, it is indispensible eg, Games, SCSI i/face, real-time I/O, etc. In conjunction with Walter Oney's "System's Programming for Windows 95" it is unbeatable. The appendix describing the Microsoft DPMI extensions is worth the price. It is the only work that addresses: TSRs with Windows, Call gate thunking and shared VM memory areas. (If you don't understand what these mean, this book is not for you; if you do then you will appreciate their importance and indispensibility for high performance apps, particularly I/O oriented ones.) I found Kauler's description of Assembly implementation of OOP innards most illuminating. The 1st 2 book chapters could be culled substantially, to a summary of x86 architecture & Assembly, and the space better used for subsequent chapters where the descriptions are somewhat thin. Since the number of books on low level Assembly hacking into Windows is just 1, and Ring 0 Assembly is the only way to handle multiple CDRs, RAID array, multi-DAT or other high throughput I/O apps -- this book stands alone, regardless of its warts. Oney's book lays out VxDs, Kauler's fills in the key gaps for direct DPMI calls, fast thunking, VM sharing and working through DOS REAL Real Mode (not V86). Kauler's irreverent style is somewhat flippant for this serious a topic.