According to an article published today in PC Magazine, an Australian IT services firm has updated what it says is one of the few fully transparent studies comparing the costs of running Linux versus Windows– and found that Linux is still cheaper.

The new study, from Melbourne-based Cybersource found that Linux installations can be up to 36 percent cheaper to install and run over a period of three years than comparable Windows systems, though subscribing to enterprise technical support and buying new hardware and infrastructure can lower the savings to as little as 19 percent.

Cybersource based its calculations–what it calls a “first-pass quantitative estimate”–on the average computer-usage requirements for an organization with 250 users over a three-year period. The costing models include expenses such as workstations, servers, networking, IT staff, consultancy fees, Internet service charges, file, mail and print servers, e-commerce servers, SQL and network infrastructure servers, Internet and LAN servers, line-of-business software, desktop productivity applications, external training, printers, and miscellaneous systems costs.

The study looks at re-using existing hardware or buying new hardware and infrastructure, and also contrasts Linux installations without third-party support with those with mandatory support contracts, such as Red Hat Enterprise Linux. The idea is that a company of any size should be able to scale the figures to apply to its business, Cybersource says.

The lowest-cost system was a Linux system without external support, using existing hardware, which cost 36 percent less than a Microsoft system on existing hardware. Linux without external support but on new hardware cost 26 percent less than Windows. A Red Hat system with a support contract on existing hardware cost 27 percent less than Windows, and Red Hat on new hardware cost 19 percent less than Windows.

Cybersource saysthat since the company is known as a Linux systems provider, it took care to stack the deck in favor of Microsoft in several ways, such as factoring out the cost of malware attacks and tripling the cost of external consultants for Linux installations.

“We’ve given Microsoft every head-start possible but Linux’s cost advantage is simply too great for most organizations to ignore,” says Cybersource chief executive Con Zymaris in a statement.