Originally Posted by Tegramon
Or is it a good start?
Itís a good start. Once you learn x86 assembly well enough, most of the 64-bit extensions are easy to get. As I said before, the only drastically different feature of x86-64 from an x86 assembly programming perspective is the instruction-pointer-relative addressing (which is similar to how RISC archs such as SPARC can address memory).
is a short list of differences for after you have learned x86 assembly.