Hi,
From a person wanting to know more about Windows Internals, reading the book "Windows Internals", and wanting to get into driver development, is learning COM programming a good idea?
How deep should I get into it? Just understand the basics or should understanding be advanced, taking into account the above.
COM isn't used much in current development, but there is an enormous amount of software still using it. Just understanding the basics should be sufficient.
Windows device drivers have nothing to do with COM. You can safely be ignorant of it.
COM doesn't have a lot of value for kernel mode driver development either, but it's potentially useful for user mode drivers. DirectShow is COM, for instance, and there's even a light-weight COM analog used in kernel mode DShow filters.
There's a lot of code out there that is COM, and legacy code takes years or decades to disappear. But more importantly IMO is the fact that a .NET assembly looks like COM objects when used from C/C++, so I think there's still some value in knowing COM if you intend to keep writing C/C++ code.
If you plan to switch to C#, Java, or one of the dozens of other languages-without-pointers that (judging from the questions here a SO) the majority of programmers have adopted, then no, not worth the opportunity cost.
On the one hand, COM seems to be Microsoft's preferred method of interoperating between native and managed (.Net) code. And to be honest, .Net does handle COM well.
On the other hand, in the immortal words of Lino Tadros:
COM is like SMOKING: If you have not started, you should not start now, if you are already doing it, it is time to stop.
Personally, I use it when I need to talk to existing COM objects (like MSXML), or if I absolutely needed to talk to a .Net assembly from native code where something like unmanaged exports isn't an option, but don't consider it useful for new development.