Demand for Windows and Linux servers is increasing at a rapid pace, at the expense of Unix servers and other non-x86 machines, according to IDC.

"Microsoft Windows server demand was positively impacted [in Q2 2010] by the accelerating x86 server market, as hardware revenue increased 6.7% and unit shipments increased 28.2% year over year," IDC says.  

Windows-based servers raked in $5 billion in quarterly revenue, representing 46.5% of worldwide server factory revenue.But there was room for both Windows and its rival Linux to be declared winners in the second quarter.

Linux-based server revenue grew 30.1% to $1.8 billion year-over-year. "Linux servers now represent 16.8% of all server revenue, up 2.5 points over 2Q09," IDC says.

Overall, server sales posted their biggest jump since 2003, with an 11% increase in revenue and a 24% increase in server unit shipments.

The demand is mainly being driven by x86 systems. "IDC expects the recovery to extend to Unix and mainframe platforms in the second half of 2010," the research firm says. But in the second quarter, Unix server revenue declined 7.3% year-over-year "as customers waited for details about the IBM Power Systems servers."

The total market for non-x86 servers declined 16% to $3.9 billion in quarterly revenue.

Among systems vendors, HP led the way with $3.5 billion in revenue, followed by IBM with $3.2 billion and Dell at $1.7 billion.