I just got done reading basically all of Vol. 1 (Basic Architecture) of the IA-32 Architecture Software Developer's Manual, with the exception of these sections (yes, I know 3DNow! is AMD, but you know what I mean). I'm about to start in on Vol. 3, the System Programming Guide. But before I read that, am I doing myself a huge disservice by skipping the reading on these processor extensions for now? I've got the general concept down -- single instructions that perform a single operation on multiple operands packed into a larger register -- but I'm not sure if these extensions are implemented frequently enough in a typical program to concern myself with the details for now. Can these generally be safely ignored by a beginner, or are they so common that it's inevitable that I'll have to deal with them sooner rather than later? I can't say that any of the programs I've fooled around with so far have used them, but maybe I've just been lucky.

P.S. Does Intel have a freaking copy editor? I swear no one proof-read their manuals - errors all over the place.