Having a legit copy of XP is pain in the ass. I upgrade my computer at least 4 time in 1 year, not mentionning that I try many type of PCI card, end up with messed OS and drives base at least once in a month, reinstalling at least every month. 3 install in one week can happen.. even if it is not what I intended first. When I install XP, I install it just like I would not have to reinstall it soon. but.. sometime I have too.
I just build a nice system 1 month ago, and someone want to buy it. I'll sell it and try another brand of board. So, activating sometime twice in one month, reinstalling 4-5 times in one years is not really my favorite time. Either it is an otomated activation or I talk with someone, which is boring. I could now have lot of friend at MS if I had to call everytime I reinstalled my XP. See, installing take less than 40 minutes.. You really think I'll spend more than 30 minutes trying to fix something that went wrong??? Everything is up to date on my HDD and i don't have to run for every apps I have on my machine.. It just sit there somewhere waiting for the next reinstall.
I sometime try to replicate users errors to understand what went wrong, and how to fix it. You hear it ok.. I mess up my computer sometime with apps others had and that messed on their system trying to find a fix. Yes, I build/fix computer for other. No, I don't sell pirated XP. My legit copy is..well, somewhere with other old installation CD from various motherboard..
Anyway, I don't use it anymore... I have a slipstreamed SP2 XP.
So, why using a version of XP that don't need validating? More pratical for me, can try winupdate in case that one update could have messed up somebody else computer I have to fix. Media player one time would not play nice with some codec on a system I had to fix... Messed up mine, had to get media player more than 3 time in a short lap of time so that mean fresh install and updating too often.
Why not linux? Who tell you I don't have or tried linux? But, imposing linux to a novice as a fix would not help me to keep my customers..