5. Check Your IDE Port Mode
First check what mode your secondary IDE port is currently working in. Go to Device Manager: right-click on My Computer, select Properties, click on the Hardware tag, click on the Device Manager button, click on the plus sign to the left of IDE ATA/ATAPI Controller, double-click on the secondary IDE channel, click on Extended Settings and check whether it is set to DMA when available. Directly underneath that setting is a grey field that shows the actual working mode of your IDE channel. You want the highest possible DMA or Ultra DMA mode there, and you definitely don't want PIO mode.
If the Extended Settings tab is not there, perhaps another driver is used, probably from the manufacturer of the IDE ATAPI controller. You can still perform a simple test. In the Task Manager activate the option View, Show kernel times. Then put a high load on the device, for example by copying a large file, and check whether the kernel times are minimal (red line). If you observe considerable kernel times, roughly around half of the total load, then the device is running in PIO mode, which is bad. The whole purpose of the DMA mode is to relieve the processor (in kernel mode) of this load.