Please realize that FreePBX is a “Gui for asterisk” not a full platform. In that regard we don’t formally recommend hardware, etc.
But you say you are looking for a simple install so to start I’d recommend looking at one of the many ISO distributions (in no particular order PBX-in-a-Flash, AsteriskNow, Elastix, etc) there are probably about 30 different distros currently. Some are better then others, some have a better community for support while others do not, so look around before selecting one, remember that almost all of them use FreePBX as the GUI so from that regard they will be the same, it’s the options they add or don’t add that make it what you’ll like or not.
As for hardware there are also a decent number of vendors available but without knowing where you live it’s hard to say who’d hardware you can get and use. The one recommendation that I will give is do not use X100 cards and if you get a analog card get one with hardware echo canceling.
The computer you run it on is as important or more important. Don’t use some top of the line just newly released system as linux support for it might be hard to come by for a while, at the same time don’t get the cheapest thing you can either and get a motherboard with just one or two slots if that is all you need. This is real important thing to know about analog cards is that the cards when installed need a dedicated hardware interrupt to work properly. Sharing IRQ’s with another slot or piece of built in hardware will cause you all kinds of problems, headaches, nightmares and loads of trouble shooting time (which is money) so spending a bit more on a decent name brand board or system instead of the cheapest thing you can get is a very wise investment.