The campaign has been created by Crispin Porter + Bogusky, with Microsoft investing $300m (£176m) in the global push. The aims are to take back some of the ground gained by Apple with its long-running Mac vs PC ads, as well as to reassure customers over the new Windows Vista operating system.
The UK ad campaign is the biggest in Microsoft's history. The company said it would celebrate the "diverse range of PC users across the UK". The ads will also emphasise Windows' ability to be used on PCs and mobiles.
The creative is based on ads made for the US featuring ordinary PC users as well as celebrities, including Pharrell Williams and Eva Longoria. In the UK, the ordinary people in the ads will be from the UK, although the US celebrities will still appear.
John Curran, who heads Windows for Microsoft UK, said: "The first stage of this 'Real PC' campaign is deliberately designed to address the misconceptions that our competitors have built around PC users.
"With nearly one billion users and 90% of the PC market globally, we're celebrating the rich diversity of Windows' users and the extraordinary connectedness they all enjoy."
The US campaign kicked off with a number of ads featuring comedian Jerry Seinfeld and Microsoft founder Bill Gates. The campaign had mixed reviews, with some people admiring the company for trying something different and quirky, and others criticising it for responding to Apple's marketing strategy.
Part of the UK campaign will encourage PC users to visit the windows.co.uk website, where they can upload 'I'm a PC' moments to a website. There will also be a video pod touring the country, which will let people record messages. Microsoft said that some of these could end up being used in later advertising campaigns online, on television and in outdoor ads.
UK media planning and buying is by Universal McCann.