Yap, that's the deal. I read somewhere that it's more advisable to have it mounted corrctly.
A couple of months ago I needed to mount my new 3.5" Western Digital HD vertically instead of horizontally in my PC as is normal. I checked with Western Digital about this and how it would affect the drive and they said that it doesn't matter at all how you mount it, you can mount it anyway you like, even upside down if you wish without any consequences for the drive whatsoever.