I've repeatedly mentioned, both here and in my previous Internet Nexus blog, that Apple's phenomenal year-over-year quarterly growth in Mac sales won't translate into significant market share gains. And of course, the ongoing PC market share data backs that up. It's easy to grow when you're small. Say HP is the biggest PC maker in the world and they sell 13 million PCs in a quarter. Apple sells 2.5 million. If they both sell 250,000 more PCs in the same quarter a year later, HP’s growth would be tiny (2 percent?). But Apple’s would be huge (10 percent, about five times higher). It’s simple math. Which, of course, I’m utterly incapable of. But that’s another story.

Obviously, this growth vs. size analysis applies to any market share-type measurement you wish to make. It’s the reason Vista’s market growth is so impressive right now (and much higher, even, than the Mac’s gains): It was a brand new release starting from zero (looked at year-over-year). It’s easy to grow when you’re small.

And the same thing applies to x64 versions of Vista, as noted in this IDG News story:

People are beginning to use 64-bit Windows Vista on PCs in favor of the 32-bit version of the OS faster than they have previously, Microsoft said this week.

The installed base of 64-bit Windows Vista PCs as a percentage of all Vista systems has more than tripled in the U.S. in the past three months.

But don't be fooled by the numbers and think there is rampant interest among PC customers in 64-bit Vista, warned one analyst, who said that prior to Vista, use of 64-bit versions of the Windows client OS was virtually nil. "If you start from almost zero it's easy to triple," said IDC analyst Al Gillen.

Exactly right.