I used to run a Jaz drive under Windows 98 and it didn't need any special drivers for it to be recognised. If the drive is a new addition rather than an existing drive that has developed a fault then it may be a setup problem. Have you terminated the SCSI chain beyond the Jaz drive? Is the SCSI card appearing ok in device manager? You can check your version of Windows 98 on the General tab of the Properties of My Computer. If it's Second Edition it will say so. If it just says Windows 98 then it's the earlier version.