I very much doubt that a computer that was built to run W98 will be powerful enough to run XP.
XP requires much more power to run than W98 ever did and I am afraid XP will probably be almost unusable.
If you can tell me the CPU type in your PC and the amount of memory you have I will give you an idea if the PC is even capable of running Windows XP.
As for answering your question, I am not sure what you have done. It depends what type of instal you did and what options you took during the install of XP.
There is a description here about the upgrade process, maybe have a look through that and see if you can see where you may have gone wrong.
http://www.winsupersite.com/showcase/windowsxp _sg_9xupgrade.asp