Off topic just a little bit,
@cas
If you are looking for a good Linux system, I recommend Ubuntu-Gnome. They do away with the god-awful Unity Shell, and replace it with the Gnome 3 desktop environment. You still get all the benefits of vanilla Ubuntu (updates, applications, and upstream bug fixes) but with a usable workflow instead. If you are looking for Linux, then IMHO Ubuntu-Gnome is the way to go right now.
Whats wrong with windows 8? 
Ive used it for over a year now, and so far its been fine for me. I hear alot of bad shit about it, butmy only issues are as follows :
-It thinks I have a pirated copy, which is annoying but probably my fault
-The start menu is pretty useless
With windows 8.1 you can boot directly to desktop if you prefer. Ive never had any compatabilty issues or any other problems I would assosiate with the operating system.
You can fix the start window with classic shell/win8 start button (I think it called not in front of one ATM). My experience is minimal, but other than the PITA getting the UI back to usable for programming…no issues.
I’ve also got some Linux distro advise which I’ve posted @ http://www.java-gaming.org/topics/sorry-ubuntu-has-experienced-an-internal-error/32616/view.html
But it’s half digested by the “Chit-chat Monster” now though! :-\
Luck I’ve saved my post offline and gonna re-post it here! :
[spoiler]
Go to http://DistroWatch.com to get the picture of all open source distros. Roll Eyes
In general, any Ubuntu derived distro is good for 1st lookers.
As mentioned, Mint is overall the better choice. Zorin is good too.
But if you’re inclined to more aesthetically gifted distros, I’d go w/:
Elementary -> http://DistroWatch.com/elementary
or Deepin -> http://DistroWatch.com/deepin
For lighter Ubuntu-based distros, go w/:
Bodhi -> http://DistroWatch.com/bodhi
LXLE -> http://DistroWatch.com/lxle
For non-Ubuntu & non-DebIan options, perhaps these 3 below:
PCLinuxOS -> http://DistroWatch.com/pclinuxos
Fedora -> http://DistroWatch.com/fedora
OpenSUSE -> http://DistroWatch.com/suse
If you feel pretty adventurous, there’s PC-BSD -> http://DistroWatch.com/pcbsd
Which it’s not even a Gnu/Linux distro, but a FreeBSD 1! Tongue
[/spoiler]
Make a wiki page and support why you think these are good ideas. I’ve started to peek at CentOS…I’m going to look at the other light wight disto’s you mentioned.
Alternatively for the same money you could buy a small collection of Android test devices. 
What ELSE is going to be done with this machine I wonder?
Is noise/power consumption a factor? If the computer is in the living room you’ll go nuts if it constantly sounds like a vacuum cleaner.
Being fair a decent after market fan will cost around £20, most GPUs can run idle with there fans at 5%.
I do not hear my i3s fan, or my 7870XT unless I start playing games.
I’m okay if there are “hijacks” off the topic, as long as it generally stays pertinent to issues concerning purchasing a new computer with an eye towards supporting an Android development environment.
I may just get a Tablet as a first step, as suggested (thanks again for making me aware that this could work!), and and take it from there. It might be possible to push back the purchase of a new computer yet a few more months (with the hope we become a true dual-income family again in the meantime).
Meanwhile, I can switch over to my Ubuntu partition (I am dual-booting anyway) for all Internet access, drop the use of XP in that regard. Pain in the butt, but frugal.
I never did give my opinion about the computer in the op.
For the price? It could be better, you need to build one… It is cheaper and very easy. It’s kind of like Lego but with screws and wires 
You can get Z77 chip set motherboards (faster fsb, better overclocking, slightly more future proof) 8GB of Ram at a died of 1600mhz. All roughly the same price when bought from the right place.
Also tgr upgrade options such, the motherboard for instance is terrible. I’ve had very bad luck with thst range back when I had core 2 duo/qx9xxx setups.
Also a higher wattage PSU for future updates.
Why not buy a 2nd hand desktop computer for ~$100 off a friend / ebay.
It would sure beat your current setup by a factor 2 or 3.
You can take the same approach for your tablet - who needs new toys anyway?
Very much this. If not a friend then preferable one you can go check out locally.
Buying a computer at a local store would cost much more than if you were to buy it online.
Or at least that is so in my area 
Cheapest would be to buy someones second hand gaming computer, but i understand this is no fun.
Second would be to buy the components separately on the web and assemble then (or make a friend do it for you).
Then complete desktops web
Then complete desktops retail.
If you just pick an AMD A8-xxxx APU you have for <100 bucks a nice processor + vidcard, will surely be enough for the not ‘die-hard-gamer’, for you way more than needed, if I see how long u have lived with such an old pc or maybe I have to call it ‘wooden pc’ or ‘oversized gameboy’. (Salt please!)
Motherboard, Case, 8GB memory and a small PSU (300W is more than enough for a setup like this).
Oh yeah, I recommend a Samsung 840 EVO 120GB as well, but they are like 70 bucks so if you don’t have the money you can always buy one later since you still need another hard drive for some storage whether you buy that SSD or not. Price: ±400 bucks total.
Heh, you may think it’s funny but it’s the reason I just multithreaded everything in Battledroid - Alli’s computer has a weak 6-core Phenom in it and only managed 20-30fps a month ago. Now we’re all cooking on gas at a steady 60fps.
Cas
I was serious! ;D
For the power supply the most important thing is not the wattage but the overall quality of the psu.
The one built into “system 2” is most probably low quality.
Don’t be afraid to pay around 100$ for the psu.