Netbook sales are slowing as people consider buying tablet computers – particularly Apple's iPad – instead, according to data released separately by research companies Gartner and IDC with their analysis of third-quarter computer sales worldwide.

Overall, sales of PCs grew slower than had been expected. Gartner said 88.3m were sold in the third quarter, up 7.6% compared with the same period a year ago when 82m were sold, but below its earlier forecast of 12.7% growth (which would have meant 92.5m sold).

IDC, which uses a different method to measure sales, said there were 89.7m sold, up 11% (80.8m) but nearly 3% below its expectations (which would have seen 92m sold).