I haven't used the first version of XP. However I was glad to switch to it from 98 SE after getting a stable version (I thought most of the users as well). I waited for a year but I got XP SP1 that was rather good. As for Win98, it is not secure I suppose. It is good for old computers 'coz it is the only OS that works fine on them.

Vista is different. Lots of programs won't work on it. And it still has lots of problems with hardware. And my guess it that it will take more time to get a version that will be good for most users.