Sorry, but I gotta agree with the majority...............there are too many missing things in your question for me to give you a general answer. It depends on what you like to do. What you are using it for and mostly if 98se is working for you right now why would you want to switch just for the sake of switching?
If you are using 98se and you are wanting to update just for the sake of updating, but 98se is doing the job the WHY? The bottom line is if it works use it.
I guess I repeated myself enough didn't I? But, having a OS that works is the bottom line.