I just got a new HP with XP home. I use to use 98se. IMO, XP is 1000% times better. For work, I run a large amount of Java applications and it just handles it much better. Alot of it has to do with the hyper threading feature and I'm running a Pentium4 with 2.8GHrz as opposed to 900Mhrz on my old computer, but the archetecture of XP seems to handle resources and just about everything else better than my 98se.
It might be for handling larger applications and overall stability XP is better than the rest. The main problem with 98SE is that it starts out good but gets bogged down quicky from installing and uninstalling programs and so it has to be reinstalled more often. XP can go a lot longer without having to do a reformat.
But still for surfing and burning software like Nero I find 98SE is more efficient and easier. For some reason Nero's latest, Ultra 6 doesn't have their built-in lame encoder included in XP but it is in 98SE, I'm beginning to wonder if it's being disallowed in XP somehow and if that's a sign of things to come.