Linux continues to be the global growth leader among operating systems in both revenue and units, according to the latest market research from Gartner.

The analyst group noted that Linux grew its global revenue 55.7 per cent from last year, and increased units by 45.2 per cent.

Windows gained another two points in market share for all operating systems over the third quarter of 2003, earning 36.5 per cent of all revenue, or about $4.3bn for the quarter.

"The server market is still being primarily driven by the x86 segment," said Mike McLaughlin, principal analyst for Gartner. "This, along with the acceptance of Linux in additional application areas in the enterprise space, will continue to drive demand."

The analyst firm found that IBM held its lead based on server revenue, as its market share remained at one third in the third quarter of 2004.

Dell continues to lead all major vendors in growth, boasting a 17 per cent revenue hike this quarter and overtaking Sun Microsystems for the third spot overall.

According to Gartner, worldwide server shipments surpassed 1.6 million units in the third quarter of 2004, representing a 16.3 per cent increase from the same period last year.

In terms of overall volume, HP led all vendors with 468,924 units shipped in the third quarter. Dell experienced the strongest growth rate among the top five vendors, as shipments increased 25 per cent from last year.

Both Unix and 'other operating systems' categories continued a slow decline, the study found, with revenue decreases of 3.6 per cent and 5.8 per cent respectively.

In EMEA, the server revenue market reached $3.5bn in the third quarter, a three per cent increase from the third quarter of 2003. Shipments totalled 468,000 units, a 19 per cent increase from the third quarter of 2003.

Adrian O'Connell, principal analyst at Gartner in EMEA, said: "Although shipment growth dipped below the 20 per cent level for the first time in six consecutive quarters, this was still a very positive quarter.

"The replacement cycle continues to drive volumes, but we are seeing indications of strength across the market. Demand was particularly strong in Spain, Switzerland and eastern Europe."