If by "needs", you mean being able to access many of the common websites that many people visit today, as opposed to what was in existence 15 years ago, then the typical desktop user's needs have changed. He did say desktop as opposed to dedicated PC that he uses to run a couple pieces of particular software. Also, whatever he's doing, he obviously wants more performance, that's a change in needs that suggests whatever he's doing, it isn't doing it well enough today. And like I said before, IDK of any browser supplier that still supports XP. It seems very odd to me to be spending money on a new CPU, memory, HD, etc to upgrade an XP system that you're going to use as a typical desktop PC at this point, with the lack of a supported browser being a big point.
The thing I've seen is that more and more websites either won't work at all, work but then have a problem at some point or just don't work well with an old browser. You can use Ad Block or similar to block ads.