Can you post the exact illegal operation error message?
If you have no Windows 98 CD or drivers for the PC you will need to get as many drivers onto CDR CDRW as possible before doing anything else with it, to do this you will need to find what is inside the pc and visit the manufactureres website for the software and drivers related to them. I would ask the person who gave it to you if they still need the windows 98 CD.
This will help you find out what is inside the PC
http://www.lavalys.com/products/down...?pid=1&lang=en
is it a branded unit at all? Time/ Tiny? packard Bell etc?