Then skip to the Recommendations . If you want a controller for hard drives, you want to get at least an Ultra2Wide controller, but you might as well get the Ultra160 controllers instead since there isn't much of a price difference.
Transfer rate is another thing to consider.
You might not even notice the difference with 4 hard drives connected. Max simply means that all drives on the card can transfer a total of up to 160 MB per second. Since 1 drive will not currently transfer data nearly that fast, it's pointless for a single drive. Number and type of connectors are obviously important. The Chipset on the SCSI card is also important, but I don't know a lot about the chipsets.