If you have loaded DX8.1,..make sure you get the latest video drivers from ATI's WEB site. If you installed the video drivers from the CD that came with the card, then....
1) Go to ATI's WEB site (
http://www.ati.com) and get the latest Catalyst drivers for your video card. Save them to a directory on your local HD.
NOTE: These drivers will require DX8.1. If you have not installed it, then go to Microsoft's WEB site and get DX8.1 and install it.
2) Go to Control Panel and use the Add/Remove Software utility to remove the ATI software
3) Reboot (at that time you will be in VGA mode,...dunt panic)
4) Now, run the file you downloaded from ATI's WEB site. It will install the drivers for your card.
5) Reboot after it is complete and setup the video display to your liking.
6) Make sure your monitor is detected correctly. If it is not, then install the INF file for it.
128MB of ram with W98 is plenty.
Hope that helps.