You make the mistake of thinking that XP is somehow better than 98, in much the same way that a Radeon 9800 is better than a Radeon 7500. And that my friend, is a filthy, dirty lie.
As I said, for anyone other than a housewife who's sole concern is how to send email and "keep safe from the hackers", XP is just needless, unwanted crap. It takes up more resources, is more restrictive, and puts more control in Microsoft's hands.
But wait! Its the newest one! That means we HAVE to buy it, cause its the newest one, and if you don't buy a new OS every 3 years, you're obviously stupid and should not be meddling with technology.
I'm not going to install whatever piece of spyware-ridden junk Microsoft chooses to label as an OS and sell for $500. If I wanted to do that, I'de buy a Mac and install their "upgrade" every few months, and fork over a few hundred bucks.