CPU:At present, I believe the Intel 'Core' range is still better than
the equivalent offering from AMD. Do not be concerned about GHz these days... it is no longer the indicator of processor grunt that it used to be. This is especially so in the case of multiple core CPU's... It will still tell you which CPU's in a particular model are better (ie. for Core 2 Duo: E6700 @ 2.66 GHz > E6600 @ 2.4 GHz > E6400 @ 2.13 GHz > E6300 @ 1.86 GHz etc.), but you cannot say that a 2.66 GHz C2D is worse than a 3.0 GHz Pentium 4 etc...
Also, AMD chips have been running at lower speeds for a while, but still performing... my old Athlon XP 2000+ was the equivalent of a Pentium 4 @ 2 GHz... but it was only running at aroun 1.3 or 1.4 GHz from memory... (this is why AMD invented the whole XXXX+ numbering thing)
RAM:Realistically, 1 Gig is not enough... you will find that XP runs adequately with this (Vista will not)... but FS would definitely benefit from 2+ Gigs...
Motherboards:Probably not the best boards in the world... but unless you are an extreme overclocker and like to twiddle and tweak every last little MHz out of stuff, they will probably do the job...
Although I do note that the Intel one only supports 667MHz RAM, and only up to 2 Gigs... so it does not have a lot of room for expansion.
Graphics:It would appear both of those boxes, by default use the onboard VGA of the mobos... however they both have PCIe x16 slots... so you should be able to go and get a nice 8xxx series nVidia card... just remember to factor in the extra $$$...
PSU:Both of these boxes are woefully underpowered... especially if you are going to stick a nice graphics card in them... (eg nVidia 8xxx series). I would be looking at 450-ish W...
minimum. But if you're going to use onboard video

, then it should be fine.
OS:As far as I can tell, they will not come with any OS... the idea of upgrade boxes like this is that you use as much of your old gear (keyboards, monitors, mice etc) and software licenses as possible...
Might pay to ask the PBTech guys...