One of the biggest threats to small software businesses and freely available open source software is the threat of software patents.
Software is already protected by the current copyright laws, patents are not needed to prevent people stealing other peoples software. The big problem is that software patents could be applied to very generic terms, and make it virtually impossible to write competing software. It would be possible to violate several thousand patents when developing a piece of software, and finding out which ones applied would be a difficult task.
The only way for the free and open source software such as those listed at: Free Computer Software for Windows XP, and the Linux Operating System is to ensure that software patents are not allowed.