The reason is probably that XP has set your IDE drives into PIO mode instead of DMA! Remedy? Enter the device manager by right clicking “my computer” and choosing “properties” and then “hardware”.
Double click on the “IDE primary drive” and then “advanced settings”. There you can see the current setting for the master and the slave drives on the primary IDE channel. There you can select transfer mode. If it is set at “PIO only”, then select “DMA if available” instead and reboot!
If the computer persists on having only PIO after reboot even though the hard drive is a flashing super-duper ATA133 and transfer mode set to “DMA if available”, then you have to do the following:
Remove the primary device in the device manager and reboot! Voilà, now the harddrive should be running in DMA mode.
Repeat on the secondary IDE channel if necessary.
Now enjoy your smooth running DivX;-) and mp3s and the overall increased performance of your computer!
(Note: You will not see the Advanced Settings section if your hardware does not support it)