Hewlett-Packard Co, the world's biggest PC maker, will help sell online backup services from Symantec Corp, which is looking to expand its consumer business beyond its line of Norton security products.

Symantec said on Thursday that HP will ship all the personal computers it sells to consumers with preloaded Symantec software that offers subscription to an Internet-based PC backup service.

They will be offered a free one-month trial for Norton Online Backup, followed by an annual subscription for $50.

The backup service is one of several cloud computing products that Symantec has introduced over the past year in a bid to boost sales.

Analysts believe that cloud computing will be among the fastest growing areas in technology in the coming years. It refers to the use of the Web to access services from remote data centers.

Revenue at Symantec's consumer unit grew just 3 percent in its most-recent fiscal year to $1.7 billion, down from growth of 10 percent a year earlier.

It could take several years for the backup product to substantially boost sales.

Technology research firm Gartner estimates total sales of all Web-based backup products will rise 23 percent this year to $370 million. Symantec's competitors include EMC Corp's Mozy division and privately held Carbonite.

Symantec also offers cloud-based services for repairing PCs and letting parents monitor use of family computers.

The company already has a PC distribution agreement with HP, through which it sells Norton Internet Security, a suite of programs to fight hackers and other threats.

Software makers covet such deals because consumers like the convenience of purchasing programs right from their PC desktop. The world's top PC makers have similar relationships with various software companies.

HP and Symantec have declined to say when the security software agreement is due to expire. No. 2 security software maker McAfee Inc has said it hopes to woo the contract away from Symantec.

Symantec consumer division president Janice Chaffin said that she intends to renegotiate a new contract when the current pact expires.

Symantec shares were down 1 percent to $16.28 in late morning trade as the Nasdaq Composite Index rose 0.7 percent. HP shares were up 1.3 percent to $37.26 on the New York Stock Exchange.

(Reporting by Jim Finkle; Editing by Tim Dobbyn)