Reading, ran across articles stating MS had intended to release Win2k SP5 but abandoned the idea. That resulted in more searching and eventually landed here:
https://twilczynski.com/windows/updates/
This may be the motherlode, think I'm gonna go through those see, what they are (as far as files) and see if there's any potential replacements in Windows XP/POS09 updates. I'll keep the POS09 ones strictly the ones that I believe are non-SSE2. I may just jump in here fairly soon and install Win2k.....