Microsoft has emerged victorious from a lawsuit over a patent on faster boot-ups.

The suit, filed in Texas, charged Microsoft with infringing on US patent 5,933,630, which was issued in 1999 to Acceleration Software International. The suit asked the court to award the patent holder $2.50 per copy of Windows XP sold in the US. By Microsoft's account, that could have amounted to $600 million to $900 million.

Microsoft argued that there are many ways to improve the boot speed of PCs and that XP uses different technology than that in the patent.

The jury found that Microsoft did not infringe on the patent and that the patent is invalid because it was obvious and because the technology already existed. The judge is still considering Microsoft’s assertion that the patent holder wrongfully withheld information about the existing technology when filing for the patent.

Acacia, a company that buys patents and enforces them in court, is behind the suit. Acacia bought the patent and formed a company called Computer Acceleration, which filed the action against Microsoft.

The plaintiff late in the case sought to add a claim against Vista but the court denied the request.

This is the fourth suit that Acacia or its subsidiary companies have brought against Microsoft. One was settled, another Microsoft won during a summary judgement, and another was just filed on Monday, Microsoft said.