Gates told delegates at a conference in Cape Town that there was an "80 per cent chance" that the software would be ready to ship as scheduled by January 2007.
Microsoft announced a delay to the launch of the software in March. The company's developers originally planned on releasing Vista by the end of 2006, but said that they needed additional time due to quality issues.
"We have target dates for availability, but as always the exact delivery date will be determined by quality," a Microsoft spokesman told vnunet.com.
"We have had overwhelming demand for Windows Vista Beta 2 for testing, and have received positive feedback about the product's progress.
"We are continuing to take input and improving the product, and expect to unveil Release Candidate 1 in the third quarter of this year."
Windows Vista is currently in the Beta 2, or public testing, phase and about 2.5 million users have downloaded a copy or ordered a DVD.
Microsoft developer Robert McLaws reported in a blog posting last week that the software contained 5,743 active bugs as of 3 July, leaving about 20 per cent of the total number of reported bugs still to be repaired.
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