You're right, if you say 'N' to something, the it doesn't get compiled.
Saying 'Y' to something means that it gets compiled striaght into the kernel, and stays in memory all the time.
Saying 'M' compiles the module, but allows the kernel to load the piece of code only when it's needed, so freeing up RAM.
Having components compiled into the kernel is slightly faster when in use, but uses RAM all the time. Compile times are pretty much the same either way, because the component still has to be compiled whether it's a module or in the kernel. The kernel size gets smaller the more components you compile as modules.
If you're using a component all the time, then compile it in. If you only need the component sometimes (e.g. USB storage, etc) then compile it as a module. You should have your / filesystem (ext2/3 / reiser or whatever it is) compiled into the kernel, and any drivers you need to get the system to boot.
Last edited by ilikejam; 02-22-2004 at 06:46 PM.