[Jakesty]

Originally Posted by scooterspal

Does this assume the HD is connected directly to the MB via an ATA cable?

That is, if I use external USB or Firewire enclosures for my drives can I still safely get these #'s or at least safely record 4 to 8 channels at the same time?

It would seem, then, that SATA drives are not required to make multichannel SD video recording a reality. Regular ATA drives can do the job easy enough. Is this correct?

Most people have had mixed results with USB. The drive isn't the problem, it's the bus through-put of the USB.
Sata drives aren't really any faster than PATA, but unless PATA drives are your only choice, you're buying technology that won't be as easily supported in the future. (I'll preface the speed comparison with drives of equal size. The new 1.5tb drives are supposed to be much faster, well over 100mb/s.)
Like what was said earlier, speed of the drive isn't everything. Some of the data is closer together. Drives today are recording perpendicularly, making it faster to read as well.
My older 500gb Seagates, 7200rpms, I recorded 6 shows, 3sd 3hd, while watching a program all at the same time. OS separated from the DATA drives. Like what Rich says, I have had the same experiences as well. 2 drives effectively doubles the speed, but it may not be necessary given my results. But that speed is so nice when you try to do anything at all and need something done NOW.