We are living in a difficult time; the economy is still in the process of recovery with no indication for an end to this crisis. enterprises are forced to change their strategies and adopt new ones in order to reduce the cost of the enterprise operation. This puts pressure on the IT departments as the enterprise scale proprietary software costs are among the most expensive parts in the department and without them the enterprise business can't continue.

With open source the situation differs. There isn't any ownership cost, upgrade costs, or renewal costs. The only thing that you are optional to take is the support. Even with that the support plans are usually much lesser than any proprietary software with many plans of support that suites small companies until enterprise mission-critical support.

So it is not strange that the primary reason why IT managers are related to cost saving. As reported by Gartner in its survey "User Survey Analysis: Open-Source Software, Worldwide, 2008", it has been found that lowering the cost of license and ownership plus lowering the cost of support are the top reasons why IT managers adopt open source software. Most of the surveyed IT departments are planning to start adopting open source software within the next 12 months [1].

Nevertheless, the cost saving doesn't compromise the functionality, quality, and performance of the open source software. As Gartner showed that there is an increase in the reliance of open source solutions in mission-critical applications [2]. Also, Forrester reported that 87% of companies saved money from open source software while 92% felt that the software met or exceeded their quality expectations. This shows the overall maturity of the open source in the market[3].

Resources:

1- Gartner Website

3- Survey Finds Growing Use of Open-Source Software for Mission-Critical Applications

3- News for Web Developers