Microsoft has launched its new Windows 8 operating system and Surface tablet in a bid to revive interest in its flagship product and regain ground lost to Apple and Google in mobile computing.

Windows 8 devices and the company's new Surface tablet, which aims to challenge Apple's popular iPad head on, go on sale at midnight.

The new design of Windows, which dispenses with the Start button and features square tiles for apps, may surprise some users.

From tomorrow, it will be available for download to existing PCs and at retail locations throughout the country.

PC World in Carrickmines, Dublin 18 will be the first retailer to offer Windows 8 to consumers with a special opening at midnight tonight.

Ireland has played a key role in the launching of Windows 8 with many employees being involved in the development and testing of the product.

"Team members in the Sandyford based European Development Centre have been involved in core development, localisation and testing work - ensuring that the product was ready for launch in over 100 different languages.

"In addition, the EMEA Operations Centre is providing the logistics support ensuring its available in 56 different markets from tomorrow while our Sales and Marketing team have been working with partners, the developer community and customers over the past number of months to prepare for the launch of Windows 8 in Ireland,” said Paul Rellis, Managing Director, Microsoft Ireland.

In the US, initial demand appeared solid, but customers were wary.

Early reviews of the Surface tablet were mixed, with praise for its slick hardware, but concerns about battery life and limited software and applications available.

Investors were uncertain about the prospects for success of Windows 8, but many feel a solid launch could help Microsoft's stock, which has languished between $20 and $30 for much of the last decade.