While most hardware "just works" with PC-BSD, it is possible that you'll run across a piece of hardware that does not. If you do, you can help improve hardware support for all PC-BSD users by reporting the problem so that it can be addressed by the developers. It should be remembered that PC-BSD is really FreeBSD, meaning that any hardware that works on FreeBSD will work on PC-BSD.
If you wish to check your hardware before installing PC-BSD, a good place to start is the FreeBSD 8.1 Hardware List. Another good method is to run PC-BSD in Live Mode, that way you can test your various devices before committing to an install.
If you are experiencing problems with a device, start with a Google search for the term "FreeBSD" and the type and model of the hardware. This will let you know if there is a known issue with the device. If there are many search results, concentrate on the most recent ones as often hardware that used to be problematic has since been fixed or the missing driver will be available in an upcoming release of FreeBSD.
Currently there are some known issues with wireless devices and the developers that are fixing these problems are looking for testers. More information is available on the Wireless Testing page.
If you experience problems with a device that should work but does not or you can't find any existing problem reports for your hardware, please take a few moments to report the problem. Instructions on where to send your report and suggestions for what information should be included in your report are here.