Why buy the cow when the milk is free? While commercial software is usually worth the cost, free is better. And of the open source applications that abound throughout the world, many are as good or better than their for-pay counterparts. The "free-as-in-beer" philosophy that gave rise to Linux often also applies to apps written for the platform, with programs like KOffice giving Microsoft Office a run for its money.
And free stuff isn't limited to Linux. Here's a cross section of free, open-source applications released or significantly updated in 2010 that the CRN Test Center believes are among the year's best, either in terms of their usefulness to your customers or to you and your support staff.