I'm mostly a silent reader in this part of the forum (well most of the forum to be honest) but now I feel that I have to say that I am speechless about your opinion towards modern IT technology, or to be more precise, software. Don't get me wrong Scawen, you are on my list of few people I really look up to when it comes to writing games and without any doubt, you have done (and still am doing) a superb job with LFS.
I also agree with you that Windows XP is a very good OS, which is still going strong (in fact the hospital I work for, is running XP on all their computers) while other so claimed better operating systems have been released. Having said that, XP is reaching the end of its life and while Vista wasn't a great OS, Windows 7 clearly is in my opinion.
Since most gamers are keen on new technology on both hard- and software sides, I very much doubt that many of the LFS users are still on Windows XP.
This doesn't mean that you have to abandon them right now, in fact the question isn't even on the table as you are currently working on 3D graphics and will then continue work on new tyre physics, but as time progresses and both hard- and software are getting better and better (although you can always argue about what is better and what isn't) the content LFS is delivering to people is on a sliding slope.
Sure, photorealistic graphics mean nothing when the game plays like crap, but in all honesty, LFS could do with some more graphical eye candy.
Well, just my 2 cents on this issue and to end on a positive note, I want to thank you for all that you did and are still doing for this great game.
It's a masterpiece and will only get better with every release you do, but please don't forget in which year we are living and don't close your eyes completely for all that is possible nowadays.