Thanks for all of your responses! I am sorry I didn't include enough detail; I always seem to forget something with these extremely detailed problems...
I don't have any optical drives on the controller card; I can't even burn at 12x without buffer underruns if I do this.
The IDE card is on IRQ 10. MS System Information says that it shares this IRQ with "IRQ Holder for PCI Steering", but it doesn't share with anything else. In fact, there is currently no
IRQ sharing on this system.
I am using Nero CDSpeed 1.02e to measure drive performance. It happens to all CD drives. Both CD-RW drives are using Multi-Word DMA Mode 2. At least they do in Windows XP; DMA is enabled in Windows 98.
I have only the hard drive attached to the ATA-133 card. I am using that as the boot device. I partitioned and formatted the drive while it was attached to the ATA-133 card.
I hope I didn't forget any information this time!
Thank you all again for your help!