Software that will set up a network built from users' hard drives and bandwidth has been quietly bundled into the KaZaa file-sharing program and may also be distributed with other file-sharing programs.

Los Angeles advertising software and design company Brilliant Digital Entertainment plans to use the Altnet software to map weather patterns and to crack genomes. It also plans to use the network as an alternative file-serving system for internet ads or other content.

The Altnet software has been downloaded along with KaZaa's file-sharing software about 20 million times, according to Brilliant. Most people don't realise Altnet is present if the programs are installed together, Brilliant Chief Executive Officer and President Kevin Burmeister acknowledged.

"I don't know how happy people are going to be [about] being backdoored," said Neal Goldman, research director of Yankee Group in Boston. "It didn't feel like it was above board."

People downloading KaZaa for file trading may not realise they have also downloaded Digital Projector media player which is necessary to play Brilliant's 3D promotions and advertisements for music. Altnet Secureinstall and the media player are used together as a platform for the Altnet network. Both are distributed as part of the software bundle for file-sharing programs such as KaZaa and StreamCast Networks' Morpheus, according to Brilliant.

Users often skip reading the terms of service when installing software and most people probably don't know that they installed Brilliant's software when they set up KaZaa on their PCs, Burmeister said. However, "in the interest of full disclosure, it will spawn a (terms of service) window allowing people to opt in."

Brilliant's terms of service include: "the right to access and use the unused computing power and storage space on your computer/s and/or internet access or bandwidth for the aggregation of content and . . . distributed computing," without the right of compensation.

Perhaps surprisingly, Brilliant plans to incorporate Microsft digital rights management into its separate network, allowing anti-piracy technology to sail into home computers in the wake of KaZaa, a program the music and film industry considers a piracy threat.

"End users that propagate their own content using KaZaa won't be affected," by the digital rights management software, Burmeister said. The digital rights management software will be used to build a system for micropayments through Altnet, allowing content owners to get paid a small amount each time their property is distributed through the network.

Users will be compensated for their participation in Altnet, though the company hasn't yet figured out how. "It will be incentive-based," Burmeister said, noting that it will be more compensation than simply being allowed to continue file-sharing with KaZaa.

Grid computing harnesses the unused processing power of computers in a network to analyse information in small chunks. A data set is broken into pieces and scattered through the internet to home PCs. The participating computers crunch the data, and then the processed bytes are sent back to the central project server.

Pioneered by Project Serendip (the Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations), companies have been looking to capitalise on grid computing for commercial research, such as analysing genome information for pharmaceutical companies.