Apple has refreshed its iMac desktop line, which now sport Intel's second-generation quad-core processors and the new Thunderbolt connectivity technology that debuted in February on the company's MacBook Pro laptops.

The update was anticipated, with rumors swirling over the last week that Apple would upgrade the iMac, which was last refreshed in July 2010.

Apple today updated its iMac line of desktop computers with new Intel processors and Thunderbolt connectivity.

"It's really, really hard to be splashy with desktops," said Ezra Gottheil, an analyst with Technology Business Research, essentially reprising his take last February, when he called the MacBook Pro update "ho-hum."

As is its usual practice, Apple retained the price points of the earlier models, with the smaller 21.5-in. iMac starting at £999 and the least-expensive 27-in. desktop selling for £1,399.

All iMacs now come standard with an Intel's Core i5 quad-core processors -- Apple has ditched the low-end Core i3 dual-core processor found in 2010's systems -- although buyers can upgrade to a faster Core i7 quad-core chip. This is the first time that Apple's offered processors from Intel's "Sandy Bridge" architecture in its iMac line.

Apple's 21.5-in. iMacs are powered by a 2.5GHz or 2.7GHz Core i5, come with 4GB of memory standard, and feature a 500GB or 1TB hard drive. The lower-priced model ships with a Radeon HD 6750M graphics processor from Advanced Micro Devices (AMD), while the £1,249 system relies on a Radeon HD 6770M GPU.

The 27-in. iMacs boast a 2.7GHz or 3.1GHz Core i5, 4GB of memory, a 1TB drive, and the Radeon HD 6770M graphics processor.

Apple also added Thunderbolt, the I/O (input/output) technology developed by Intel, matching the move of late February when it unveiled the faster connectivity hardware in the MacBook Pro.

Thunderbolt offers direct bi-directional connections to high-speed peripherals such as data drives, and using optional adapters, to other technologies, including FireWire, USB, Gigabit Ethernet and Apple's DisplayPort.

Apple's desktop sales have been lacklustre of late, accounting for between 26% and 39% of all Mac sales in the last two-and-a-half years.

In the first three months of 2011, Apple sold just over 1 million desktops, which accounted for only 27% of its computer sales for the quarter. That's the lowest percentage since the July-September quarter of 2009. During the final quarter of 2010, Apple sold 1.23 million desktops, which represented 30% of the company's total system sales.

In those two prior quarters, Apple's desktop sales dropped 1% and 12%, respectively, compared to the same period the year before.

But the iMac refresh should result in a short-lived bump in desktop sales, said Stephen Baker, an analyst with retail research firm NPD Group.

"They almost always get a bump, but the size of it depends on the time of year," said Baker. "Over the last couple of bumps, desktop sales have gone from negative year-over-year to positive for a couple of months."

Desktop sales bumps typically aren't as long-lasting as Apple's updates to its notebook line, Baker observed.

"In desktops, it's a very short bump cycle," said Baker. "There should be a big increase this May over last year's May, and in June it will be pretty close to the trend levels. By July, it will be back to the negative year-over-year."

But both Gottheil and Baker believe that desktops still have their place.

"They definitely remain an important part of the computing ecosystem," said Baker. "They're the most expandable, they generally have the fastest parts."

Most households have walked away from having multiple desktops, but the larger machines are still the communal computer, said Baker. "Notebooks are personal, tablets are personal, phones are personal, but desktops are the computing device that everybody can share," he said.

Baker noted that all-in-one Windows desktops -- the configurations that mimic the iMac in may respects -- have been posting solid gains, in part because some of them support touch, something that Apple does not.

"Touch just doesn't work on a vertical screen," said Gottheil. "HP has solved that with a screen that moves to a nearly flat position."

Gottheil doesn't expect Apple to copy HP's TouchSmart design. "A touchscreen is for a different user base, at a different time and place," he said.

Last October, Apple CEO Steve Jobs dismissed touch on desktops. "Touch surfaces don't want to be vertical," Jobs said. "It gives great demo but after a short period of time, you start to fatigue and after an extended period of time, your arm wants to fall off. It doesn't work .... It's ergonomically terrible."

The new iMacs are available immediately at Apple's retail stores, some authorized resellers and via the company's online store. On the latter, the new desktops will ship within 24 hours of ordering.