I never did any real research on ATA Vs. SATA. I just read that SATA was faster and grabbed them.
Back when the AMD XP2800 was the latest thing, I got my first Seagate 80GB sate drives and ran them RAID 0. They're still going. Back when the AMD 4600 X2 was the latest thing, I grabbed a couple of WD 250GB SATA-11 drives and one of them recently failed, then the other. So! For my latest upgrade, I grabbed 4 Seagate 320GB SATA-11 drives which seem to be working as they should. But do consider this, they are the loudest, oddest sounding drives I've ever had. I kid you not! They sometimes sound like birds chirping. Apparently this is normal. Well, normal for these drives.
I never benchmark my machine because I really don't care about all that, so I don't really know how much faster, if at all, these SATA-11 drives are. What I do know is, my Asus SATA DVD burner is a lot faster than my IDE Sony and they're both the same speed drives. That could be the SATA or could be anything at all.