Trying to decided which Tower to buy (PC desktop)

If you'd like to compare CPU speeds, you can look up these CPUs on http://www.cpubenchmark.net/cpu_list.php.  You can click at the top of each column to sort the list and look up the CPU model number from there.  I recommend you sort the list by CPU Value from greatest to least.  That way, you can see which CPU can provide the best performance for your budget.  Also, I wouldn't go with a CPU that's less than 3,000 on the Passmark CPU mark column since anything below that is becoming obsolete.  Your current CPU is rated at 1,487 to give you an idea.

i3 and i5 are not the same thing at Dual Core or Core 2 Duo; i3 and i5 are the newer model classifications that Intel is branding with.  If you just need basic desktop performance, the i3 will suit you needs.  If you'd like to get more performance and better future proofing, go with the i5.

8 GB of RAM is a good starting point, but I would definitely go with the 500 GB hard drive since 250 is low by today's standards (I would recommend a 1 terabyte if that's within your budget as well).

Also understand that when buying a manufactured PC, you really get what you pay for.  A $250 computer will run like a $250 computer, whereas a $500 machine will be that much better.  I see the towers you listed are at the $250 range and they might be seriously lacking in one component to bring the price that low.  I would look into a computer that's on sale to see if there are better specs available.  Here's an example of such a computer with good upgrade options for down the line:

HP 500-281

Let us know if you have any questions!

I use i5 processors with 4 cores on one CPU and they are amply fast. These are 64 bit processors and have 8Gb of memory and 7200 rpm hard drives. The laptop runs Windows 8.1 Pro and the Desktops runs Windows 7 Pro .

Windows 8 is faster than Windows 7 and never get Home, only Pro.

Rule of thump never buy a computer without first knowing what you want to do with it, example programs you will run on it, attached devices, heavy use or light use. then decides the component of it. for example I am currently using an 6 yr old laptop running windows 8.1, with a core 2 duo T5800 processor, Ms suite install, adobe light room and Photoshop, and I'm about to install Sony Vegas pro and this running DDR3 4 gigs of memory.

running smooth, now I have no need to upgrade cause my needs haven't changed, however, if I was to get a desktop going I would use and i5 or i7 6 or 8 core  processor, make sure the power supply is no less than 500w and SSD harddisk for OS and 1terabyte for file storage.

We're wanting to upgrade our son's sluggish PC.

How old is your son, if we may ask - that is, how mature?  An investment in a new computer might better be invested in a good sturdy laptop.

He's 14 and he'll be playing Minecraft, browsing the internet, running Dragon Naturally speaking, perhaps Word or Excel.

We're just information gathering at this point.

He has Autism and is not very conscientious / responsible, so a laptop is out of the question.

I would definitely be a desktop.

i would recommend an i-5 nowadays. it is sufficient for all needed tasks; unless he wants to get in heavy gaming

here an example of a pc i made last week :
case + 600W voeding
Asus P8H77-M moederbord with Intel i5-2400  cpu
8GB Kingston RAM  2 TB HD WD
DVD-RW

thx