Overall, Upgrade Your Own PC is a useful reference for maintaining your PC. Besides tackling upgrades, it could help with upkeep of your machine.
Sandler's overview of PC lifecycles is clear, albeit brief, breaking down "PC progress" into three classes of change: compatible progress, incompatible progress and progress by modification. There are examples, but not much advice on how to apply these concepts to deciding where an upgrade makes sense.
The book tackles the main upgrade tasks, including such projects as installing a faster hard drive, installing a CD-RW, updating a PC to add USB ports, installing a new graphics card and installing a new microprocessor.
The projects are designed for PCs based on Intel's Pentium II, Pentium III, Celeron and AMD's Athlon, K6-III or K6-2. Sandler suggests that some tasks, like installing more memory or a larger hard drive, can also be undertaken on older machines based on 486 CPUs. There are also tips for older machines, such as building up a collection of external devices that can be transferred to a newer machine later.
The book usefully looks at PC basics and running an inventory to determine if an upgrade makes sense. The following chapters then concentrate on each project. There are also lots of photos, so you can see what needs to be done.