We own a Product (RED) iPod Nano. It is shiny, and the red goes really well with a Nike Dri-FIT tee we wear to the gym a lot. We bought the RED iPod out of pure vanity, not to support HIV-positive children in Africa. Hopefully that pisses off Bono, because that was our secondary goal. He's just so smug about his philanthropy.

The U2 fontman's Product RED, which has enlisted corporate support from the likes of Dell, Motorola, Apple, and Armani, is, like any charity, deserving of accolades. Up to a point.

As with all philanthropic endeavors, many of the dollars coming in – in this case, from the sale of consumer goods – goes to overhead, and whatever is left over might wind up in the hands of the needy.

So despites the tens of thousands of RED products sold, a grand total of "just" $22 million $59 million has found its way to Africa so far. Okay, not exactly small change: In Rwanda, reports the NYT, contributions of $22 million have helped fund "33 testing and treatment centers, supplied medicine for more than 6,000 women to keep them from transmitting H.I.V. to their babies, and financed counseling and testing for thousands more patients."

But in March '07, AdAge reported RED companies spent $100 million in advertising, which yielded only $18 million for the charity. (RED countered by saying it spent $50 million on advertising, generating $25 million for the charity. Critics have called AdAge's report based mostly on conjecture, and we might have to agree with them.)

So how does all this money change hands? And is all the effort even worth it?

RED is, quite literally (and openly), a brand, which means companies like Gap pay to license the name and slap it on products. The companies, then, advertise their do-gooding in TV spots and the like, and then donate a portion of sales. (The amount donated differs by company. American Express gives 1 percent of all spending on its Red card, while Motorola hands off $8.50 from each Red Razr phone.)

Cheques are written to the Global Fund, a six-year-old charity that distributes money to fight AIDS, malaria and tuberculosis in Rwanda, Ghana, and Swaziland — countries with "proven success records," though not necessarily the neediest. Meanwhile, funds thrown its way by RED don't increase funding on these projects; rather, these dollars allow the Global Fund to redirect the portion of its budget normally spent on HIV/AIDS to other areas, with RED filling the void.

So does our purchase of a RED iPod Nano help little boys and girls in Africa? Yes, perhaps, in some small way. But would we be better off writing a cheque directly to a charity on the ground there? Almost certainly.

And that's the problem with charitable giving designed by big business: Companies, for all their messages about doing good, answer only to the bottom line. Good will, which they buy through their affiliation with RED, makes their brands appear more socially conscious, which can only help drive sales. Which helps their bottom line, but not necessarily little boys and girls.

For its part, even RED will encourage you to donate directly to the Global Fund. But evidence has shown you don't: In its first five years, the Global Fund counted $5 billion in donations from public governments, but just $5 million from private companies and individuals. So that pair of RED Converse you've been eying? If you're not going to write a cheque to charity, perhaps the least you could do is buy 'em.

*This post was updated from its original version.