The main difference is that SATA cables are round and skinny, taking up less space inside your box and less likely to restrict air flow.
Technically, the SATA interface allows up to a max of 150 MB/sec transfer rates, while the current EIDE interface maxes out at either 100MB/sec or 133MB/sec, depending on whether your motherboard supports ATA/100 or ATA/133 respectively.
The catch is that the SATA interface doesn't provide any real advantage over EIDE in terms of performance. Why? Because current hard drives rarely have transfer rates greater than 50MB/sec. The only exception is a RAID array with multiple drives. Sometimes the extra headroom that ATA/133 or SATA provides is helpful. But most of the time, it won't matter to the average user.
~cdogg
[tab]"The secret to creativity is knowing how to hide your sources"
[tab][tab]- A. Einstein