More than anything else, if you want this to run on real hardware, you absolutely need a copy of your processor's manual. The Intel manuals (http://www.intel.com/products/processor/manuals/) are invaluable. They go over everything from switching modes (real/protected) to virtual memory management (if you choose to go that far) to making syscalls (if you ever get to doing user mode). Most importantly they explain in great detail a number of things that must be set up for things to function, like the TSS and segment registers, that most OS texts don't discuss because they're more concerned with higher-level concepts than processor-specific details.
