According to OWC's current specifications the drive in their 5400 RPM 1TB Mercury Elite Pro container is:
Originally Posted By: OWC
1TB Western Digital Scorpio Blue Hard Disk Drive**

…snip…

**OWC reserves the right to replace or upgrade to equivalent or better components.

By the way at 1.4 Watts this particular western Digital drive uses 22% less power than the bare Western Digitals OWC is offering for sale.

I didn't look at other enclosures or drive capacities but I think OWC pretty much sticks to WD in their populated enclosures, unless the asterisk noted comes into play.

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein