You will need to get a driver from the flashdisk's website, thats if they made a win98 driver for it.
Some older flash drives had win98 drivers, not sure about the newer ones
AFAIK '98 does not support USB
Welcome to the real world. There are many businesses that still run software that will only work under Win98 or there is no need to upgrade to the latest. If a business / factory have 50 pc's, why upgrade pc's and OS if the current ones are doing fine. Many of the software packages needed to run their business can be very expensive, R30k >. Why then upgrade hardware and software and then force you to buy a new package, if you can still use the old stuff?Wow... the thought of upgrading from 98 to Windows 7. It would be like travelling to the future.
"Windows 98, especially in it's second edition (also known as Windows 98SE), handles USB fairly well" http://www.technical-assistance.co.uk/kb/usbmsd98.php