Apple is planning to charge users a $1.99 upgrade fee to enable the 802.11n Wi-Fi standard in its computers and notebooks. 

The company has been shipping 802.11n wireless networking technology in most of its Intel Core2 Duo and Xeon based hardware, but the feature was disabled pending the standard's ratification.

Apple's 17in 1.85GHz Core2 Duo iMac is the only model not to support 802.11n.

"During the past several months, Apple has shipped some Macs with the hardware to do 802.11n, but the draft 802.11n specification was not complete enough to create the required software," a company spokesman told vnunet.com. 

"Now that the draft specification is complete we are ready to distribute the software to make the 802.11n hardware in these Macs come to life."

The software that enables the 802.11n hardware will be available from Apple for $1.99. The company said that the price was due to a set of financial guidelines known as Generally Accepted Accounting Principles.

These rules require companies to charge a fee when adding "significant feature enhancements" to products that have already been purchased.

Users who purchase Apple's latest AirPort Extreme wireless hub will receive the 802.11n software at no charge.

The 802.11n wireless standard is designed to increase networking speeds to 300Mbps and increase network range by 50 per cent.

The standard is currently pending ratification by the IEEE and a final version is not expected until early next year. Current 802.11n hardware follows a draft version of the standard and is not guaranteed to work with the final version.

Apple first began shipping Macs with the Xeon chips in August, and Core2 Duo machines began shipping in September. Over the past two fiscal quarters, the company has shipped more than 3.2 million Macintosh computers.