The Linux operating system is unique, in that you
can rebuild your kernel. This allows you to add support for hardware (i.e. install a driver in Windows) or remove support for hardware that you don't have. With Pat's kernels, however, hundreds of modules are available, but they're not loaded unless the kernel detects that you have that piece of hardware. Therefore, you're not really going to notice any difference in your kernel just by trimming only a few things you happen to know about or can determine from "lspci" and "lsmod" output. They are both important -- "lspci" is very basic, and "lsmod" with Pat's kernels will show you most of your modules.
Whichever way you go, there isn't a single command to "trim down your kernel." It will take a lot of dilligent work, and learning about your hardware and how you use your Linux system.
A good place to start is Kwan Lowe's
Kernel Rebuild Guide.
As for learning about your hardware,
<Linux> - Google Search is your friend.