The owner of Currys and PC World, DSG International, has posted rising sales but said poor sales of Windows Vista-related goods will hit profits.
DSG said the disappointing sales of products using Microsoft's latest operating system would shave £20m off first-half profits.
Despite this, like-for-like sales were up 5% in the 24 weeks to 13 October.
DSG said it was "well prepared" for the Christmas trading period, when the bulk of its profits are generated.
High-definition TVs, iPods, laptops and game consoles are expected to be big sellers.
The company also said that its profit margins, dented by Vista , should recover in the second half.
But news of the impact on first-half profits pushed DSG's shares down, ending the day 8.7% lower at 124p.
Uncertain outlook
Like-for-like sales in the UK and Ireland for the period rose by 6%, with the company describing the UK market as "resilient".
DSG, announcing a total sales increase of 9% across the group, said it had also enjoyed strong trading in Scandinavia, Greece and Central Europe but that its performance in Italy had been "very disappointing".
"There is much debate about the uncertain outlook in some of our markets for the consumer environment in 2008," the firm said.
However, it added that it was "well prepared" for the crucial Christmas trading period, and said it was "cautiously optimistic that our product pipeline and market leading propositions will excite our customers".
Its Dixons stores, which once featured on most High Streets, have now been rebranded as Currys.digital, while the Dixons name lives on as an online specialist electrical retailer, Dixons.co.uk.
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