I'd say, at least according to software and hardware manufacturers, and hip gamer kids, any pentium under 2 gig is legacy
But seriously, at least the p60 and p75 are considered legacy (maybe even vintage) by the majority of computer uses... I mean, I have one of the short-lived AMD 586 processors, and it came out *after* the p60 and p75. The thing is, my Dos computer, a 486/33mhz IBM PS/1 operates much faster than my p4/2.2g running windows xp... amazing how several dozen megs of dll's can slow a computer down
And the word 'legacy' scares me... most people who call me to help fix their computers do so because they don't have a built in 3.5 inch floppy to boot their computers from... that legacy disk drive that Microsoft and other manufacturers have fought so hard to get rid of, is still a necessary item. And my old legacy Laserjet series ii prints text sharper, blacker, faster, than any inkjet printer (and just as good as any new laser printer) and it prints several thousand pages on a single cartridge (which are around the same price as inkjet cartridges now, when you buy from tigerdirect).
When I was working tech support for Dell, there were two pat statements... one was, 'Tell me what you did to mess up your computer...' and the other was, 'Your computer is over a year old, you really need to upgrade.'
Then again, there's no money to be made unless you can convince people that this year's product is better than last year's.