Just a word of caution if you're in the purchasing sector. ATA-133 drives are spec'ed to run a max burst of 133MB/sec, yes, but the transfer rate wasn't the reason why ATA133 was produced. It was a way for the HDD interface tech to overcome the 80GB (I think) limit for the ATA100 drives. So unless you 'need' 160 GBs, its better to just stick with an ATA100 board.
if youre buying a pci ide controller, you might as well get a 133, unless it is like twice as expensive or something stupid like that....for drives, worry more about access time, and overall performance. ata/133 means nothing about how the drive performs. a 5400rpm drive at ata133 is stupid, a 7200rpm drive at ata100 would be much better. so if the drive you want has ata133, then great, but dont make it a factor in your purchase. current drives max out at about 40MB/s sustained transfer.
theres not even really a difference between ata66 and ata100 most of the time....i am using ata66 on my asus a7v133 because the ata100 controller makes the boot take longer and i dont notice any speed difference, and i'm using a ata100, 7200 maxtor drive that was the fastest available (maxtor) before the current 740dx, so its not a pokey drive as far as ide drives go, and like i said, i didnt notice a difference.