You can find those drivers at the Driverguide.com site. A free registration may be required:
http://members.driverguide.com/driver/detail.php?driverid=134983
Save and expand the downloaded file on its own folder. Then follow these steps to reinstall the drivers:
Display Adapter Installation in Windows 98:
1. From the Start menu, point to Settings, and then click Control Panel.
2. In Control Panel, double-click the Display icon.
3. In the Display Properties dialog box, click the Settings tab, and then click Advanced.
4. In the Advanced Display Properties dialog box, click the Adapter tab, and then click Change.
5. In the Update Device Driver dialog box, click Next.
6. In the Update Device Driver Wizard dialog box, select Display a list of all the drivers in a specific location. Select the driver you want, and then click Next.
7. In the Update Device Driver Wizard dialog box, click Have Disk.
8. In the Install From Disk dialog box, click Browse.
9. In the Browse dialog box, double-click the folder that contains the drivers or the drive and folder to which you expanded the downloaded file, and then click OK.
10. In the Install From Disk dialog box, click OK.
11. In the Select Device dialog box, click OK.
12. In the Update Device Driver Wizard dialog box, click Next.
13. After files copy to the hard drive, in the Update Device Driver Wizard dialog box, click Finish.
14. In the Advanced Display Properties dialog box, click Close.
15. In the Display Properties dialog box, click Close.
16. In the System Settings Change dialog box, click Yes to restart the computer.