FreePbx is not an all in one installation. It is the GUI to program a telephony engine such as asterisk.
FreePbx is a component of Trixbox.
Trixbox is a full installation including an operating system, asterisk, and FreePbx.
In addition there are several “flavors” of Asterisk/FreePbx distributions including, for example, Trixbox, PBX in a Flash, Elastix to name a few.
The Trixbox distribution uses a fork of the “standard” FreePbx program, and as such what you see in this forum may, or may not be applicable to Trixbox.
Finally, the ease of installation is pretty much the same. You put an ISO image on a CD on a bare metal computer and everything is installed automatically.
You may need cards for your PC depending on how you want your system to operate.
The “forked” version of FreePBX that trixbox uses is a very old version, they “forked” the 2.5 version and puzzled together that with Asterisk 1.6.
If you need a home system that get updates and attention from the developers you should stay away from trixbox and go for one of the following, AsteriskNOW, Elastix, Fonicaprojects or PBX in a Flash.
Note, the above list is in alphabetic order and does not in any way reflect my personal choice.
If you just use the system at home, why don’t consider an IP-PBX (http://www.freepbx.org/terms-of-use) for about USD150? The FXO port is for connecting your residential fixed PSTN line. I got one receently and found it very useful. It only consumes 4W. You may google it for more information.