Office suites tend to get bundled with PCs these days, so it is hard to see what kind of market there will be for one sold off the shelf at Tesco's, even if it does cost only twenty quid. But Graham O'Reilly, of the sales team at Formjet, which has developed the software, is confident that the Tesco Office suite will find a market.

"Microsoft Office is one of the biggest retail software products in the world. People buy it off the shelf, so there is not reason whyt they should not buy another suite," he said.

He agreed that many people felt they had to buy Microsoft's product because it is a de fact standard. The Tesco product will open and close Word and Excel documents, but no non-Microsoft product is going to do this  with 100 percent reliability, if only because it would have to match the Microsoft product's feature set down to the last sub-sub-menu item. And of course one reason people buy rival products is because they believe Microsoft forces them to pay for features they don't want.

But the Formjet suite will be largely compatible, O'Reilly said. "Is everybody going to pay £300 or more for the Microsoft product when they can get something that does the same thing for a fraction of the price?"

O'Reilly stresses that the suite is not the same as the Ability Office suite, which Formjet also developed. "But obviously we will draw on work we have already done."

Two security packages, including an anti-virus product, have a more obvious market. O'Reilly was cagey about how these offering relate to Panda security products, which Formjet distributes in the UK. But as anti-virus expertise does not come easy, there is clearly some kind of tie-up.

The Tesco move does come at a tricky time for Microsoft Office, because a new version with entirely different file formats is to be launched next year. The formats are without doubt better but they do mean office across the world will face working with both the old with the new ones, which will cause hassles however much Microsoft tries to avoid them.

At the same time there are pressures, particularly from governments, for an open file format to facilitate document exchange between disparate systems. One way to increase the potential market for a rival Office suite would therefore be to use the Open Document Format which has already been accepted as an ISO standard.

The Tesco software does not use it, O'Reilly said. But he promised that the Tesco suite would remain compatible with any changes Microsoft makes to its formats.