I ran a dual boot for about 6 months (installed 2000, then put XP on top of it on a different partition). Once I figured out how to make the XP interface look "classic" it put it on par with 2000 in that regard.

Obviously, I like XP. To me it seems to be taking 2000 and making it more friendly, as opposed to taking 98 and trying to make it more durable. It has all the good qualities 2000 had, and then some.
Having both O/S's for a while let me do a lot of back to back comparisons, and it was interesting to get a new program and install it onto each. XP seems to boot faster though shut down slower. Programs and such don't seem to change in speed. Gaming benchmarks did increase a few percent however.

What's turned me on about XP (and finally after about a year I reformatted and went with it exclusively) are two things - first it is a no-brainer to connect to a network, such as setting up a cable modem or lugging the machine to someone else's house to play games. When we all ran '98 we'd spend at least 2 hours getting everyone on the network, 2000 dropped that to about an hour (or perhaps we got faster at doing it), and XP involves nothing more than plugging in a cable. Second, even though I generally don't hurt my PC and don't need it babysitting itself, there has been an instance where I staved off reformatting simply by being able to use the built-in restore function XP has.

Obviously I like XP, It's like a more user friendly version of 2000 - has all it's good points, and adds even more.