It's no secret that Microsoft is planning a big marketing campaign around Windows 8, but one estimate suggests that the company could be willing to spend between $1.5 and $1.8 billion. The huge sum, reported by Forbes, would be around triple the amount that the company allegedly spent on its Windows Phone 7 launch two years ago.

The Wall Street Journal reports that the ad campaign will kick off this weekend alongside pre-orders of some Windows 8 PCs and tablets. Microsoft has reportedly been working with advertising agency Crispin Porter + Bogusky to prepare its Windows 8 ads. Although these ads will air on national TV stations, Microsoft has also taken a less-than-traditional approach to its Surface ads. A number of ads across subway stations and walls have been spotted over the past months, with the "click in" tagline.

Microsoft will launch its Windows 8 operating system on October 26th with special holiday pop-up stores opening in US cities to allow consumers to purchase its Surface tablets at midnight. While it's not clear exactly how Microsoft will promote Windows 8, some ads leaked earlier this week — suggesting Microsoft will teach the world how to use its new OS. This is the biggest launch period in Microsoft's history so expect to see Windows 8 ads everywhere.