Microsoft has unveiled more details of its desktop security product.

OneCare will build on the antivirus software Microsoft has been sitting on since it acquired GeCAD Software two years ago, and the antispyware capability it acquired with Giant Software last December, which is already available separately.

There will be a subscription fee to pay, the company said, confirming what it has been suggesting since the GeCAD deal. But there’s no word yet on how the software will be delivered; whether it will be bundled, offered for download or sold in stores.

Where Microsoft is breaking from the pack is in bundling in PC management tools such as CD or DVD backup, disk cleanup, hard-drive defragmentation and file repair, much of which is already available in Windows but not in your average security suite.

The companies with arguably the most exposure to the Microsoft competitive threat are Symantec, McAfee, Trend Micro and Computer Associates, which all target the consumer security market. Symantec, the antivirus market leader, has been selling PC maintenance software as a separate bundle for many years. Norton SystemWorks features backup, rollback, disk tools and antivirus, but no firewall or antispyware.

If Microsoft’s move compels Symantec to add SystemWorks functions into Norton Internet Security, it will be at a time when the NIS 2005’s increasingly bloated feature set is already coming under criticism, in beta versions, for the performance hit it reportedly causes.

Microsoft has made it known that it is targeting greenfield opportunities – the estimated 75% of Windows users that do not already have antivirus installed – so competitors will not necessarily lose business.

It is unlikely that OneCare will cause as much of a stir in the enterprise space, where desktop antivirus penetration is close to 100% and security administrators know better than to rely on the same vendor for the problem and the solution. Microsoft will have to make sure it continues to tighten up Windows, building on the success of XP SP2, so it cannot be accused of putting out vulnerable software in order to drive subscription sales for OneCare.