THE most surprising thing about Apple’s hugely successful iPod is not its sleekly minimalist design, or its ease of operation, or even the pleasingly effective way it works with iTunes, the computer company’s music website.

No, the most surprising thing about the iPod is the astonishing disparity between the enormous shot of corporate adrenaline it has given Apple’s reputation and the size of the needle that injected it.

The iPod is a category-defining product that is so fashionable, so lavishly praised, so cool (to use a favourite Apple word) that it is almost beyond criticism. Apple has 58% of the market in digital music (or MP3) players, and an even bigger share of the emerging business of downloading music over the internet.

Yet look at the numbers. Apple has so far sold less than 4m iPods, but that’s over three years. In Europe, sales are probably still less than 1m.

It’s a promising start, and sales are continuing to grow rapidly, but compared with other technology markets, this is a small business. For example, sales of laptop computers topped 40m last year, according to IDC, the technology data firm, while total sales of personal computers exceeded 150m.

An even more apposite comparison is with mobile phones — many of which will soon double up as portable music players. Nokia, Motorola, Samsung et al are now widely expected to sell more than 600m handsets this year.

All of this might lead one to conclude that Apple has achieved an extraordinarily big bang for its iPod buck. Everyone is talking about its products again, and the company is bathing in a tidal wave of media goodwill, but the iPod is being used only by a tiny minority of consumers.

Despite the boost from the iPod, which generated $249m (£139m) of sales in the last quarter, most of Apple’s revenues still come from its Macintosh computer business. The Mac remains popular in education and certain creative industries, but Apple’s computer business has been in steady relative decline for years.

As the adjoining chart shows, even Steve Jobs’s much-vaunted revitalisation of Apple after he returned as chief executive in 1997 failed to do anything more than briefly interrupt the long-term loss in market share to Windows-based computing.

In 1998 — the year Jobs launched the original iMac in its coloured shell — Apple sold 3.1m computers. It sold the same number again last year, even though the overall PC market has grown substantially. According to IDC, Apple’s market share has fallen to only 2%, down a third since 1997.

It is no surprise, then, that Apple wants to sprinkle some of that iPod magic on to its Mac business. And last week in Paris, that is exactly what the company attempted to do with the launch of the new iMac.

The machine is self-consciously styled and promoted to draw attention to its family heritage. At the Apple Expo, the first image the thousands of Mac fans saw was a profile shot of the iMac standing in perfect alignment with its smaller, music-playing cousin. Just in case anyone failed to get the message, the promotional video spelt it out: this is a computer “from the creators of iPod”.

The machine certainly looks striking. Apple, and Jonathan Ive, its British vice-president of industrial design, have put the guts of the computer behind a 17-inch screen — squeezing a powerful G5 processor, hard drive, power transformer, three cooling fans and other components into a box that is only two inches thick. Phil Schiller, Apple’s head of product marketing who was standing in for Jobs in Paris, said: “A lot of people will be wondering: where did the computer go?