Microsoft shipped 900,000 Surface tablets during the recent quarter, according to data from IDC. Following rumors of strong initial Surface Pro sales, IDC says the combined total for Surface RT and Surface Pro was under just one million, with most of the units made up of Surface Pro. Microsoft entered into the top five vendors for tablet sales, with a Q1 market share of 1.8 percent. Meanwhile Apple continues to dominate with nearly 40 percent market share for its iPad devices, with Samsung in second place shipping close to 18 percent of all tablets worldwide.

While Microsoft's own Surface numbers are slow after six months, total combined shipments for Windows 8 and Windows RT tablets are also low and reached 1.8 million units in the recent quarter. IDC says Android surpassed iOS in the recent quarter to secure 56.5 percent of the market share, with iOS in second place with 39.6 percent. Combined shipments of Windows RT and Windows 8 total just 3.7 percent. IDC's figures are lower than recent estimations from Strategy Analytics. The research firm believes Windows-branded tablets have reached 7.5 percent in the recent quarter.

"Windows 8 and Windows RT tablets continued to struggle to gain traction in the market."

Microsoft has continued to keep its Surface sales under wraps. Windows CFO, Tami Reller, has previously suggested the company would "provide some updates on how things are going" in due course, but Microsoft has not yet provided any guidance. With questions over Windows 8 growth and the PC industry in general, IDC believes Windows-based tablets continue "to struggle to gain traction in the market."

The software giant recently revealed plans for smaller Windows tablets, but IDC rejects the idea of these becoming a saving grace for Windows RT and Windows 8. "Clearly the market is moving toward smart 7- to 8-inch devices, but Microsoft's larger challenges center around consumer messaging and lower cost competition," says Ryan Reith, an analyst at IDC. "If these challenges are addressed, along with the desired screen size variations, then we could see Microsoft make even further headway in 2013 and beyond."