Taking a page from burger broker McDonald's (NYSE:MCD), Apple Computer (NASDAQ:AAPL) yesterday plastered a digital billboard not unlike the Golden Arches' "over one billion served" signs you see during your lunchtime drive-through. Apple's message? We've sold 100 million iTunes.

You're welcome, Steve.

Yeah, that's right. I've contributed to the Apple downloading parade, and I'm happy for Jobs and Co. The 100 million milestone is important, even if it is mostly symbolic. For one, it furthers Apple's reputation as the global leader in music downloading at a time when a new market -- Europe -- is very much up for grabs. But more importantly, it makes the iPod an even more attractive purchase for the uninitiated. (That is, if Congress doesn't kill it, and the attorney general doesn't proclaim it a threat to national security.)

Indeed, as goes iTunes, so goes the iPod. I realize many of you fellow Mac users will call me out for saying so, but ask yourself: How much greater was demand for the iPod after the iTunes music store for the PC opened last October?

Don't remember? Here are some numbers: In the quarter the PC store opened, Apple more than doubled its sales of iPods, to 733,000 units from 336,000 the quarter before. (Sales haven't slowed: 807,000 iPods made their way into homes from January to March.)

And does it strike you as pure coincidence that Apple will take the iPod Mini overseas on July 24, not even a month after launching iTunes in Europe? It shouldn't.

We've criticized Apple's overhyping of iTunes in these digital pages for good reason. After all, iTunes is unlikely to ever contribute substantially to Apple's revenues or margins. It probably doesn't sell many computers, either. But it does a damn good job of selling iPods.

And that's really the point, isn't it? The iTunes music store provides a moat around the iPod, protecting it from attacking clones such as Dell's (NASDAQ:DELL) DJ, Sony's (NYSE:SNE) rejuvenated Walkman, and Microsoft's (NASDAQ:MSFT) recently proposed portable media player. Indeed, with so much competition, Apple needs iTunes now more than it ever has.

Hungry for more Fool iPod news? These ought to whet your appetite:

What's your take? Do you care that users have downloaded 100 million songs from the iTunes music store, or is it just more Apple hype? Debate this and other topics at the Apple discussion board -- only at Fool.com.

Fool contributor Tim Beyers just can't seem to please Mac users, even though he's one of them. Tim owns no stake in any company mentioned in this story, and you can view his Fool profile here.