That dusty old box on your desk has gotten slow and unreliable, so it's time to upgrade, but the list of options today is long and confusing. Does your PC need a quad core with DDR3 to support your USB3 SSD? Does the LCD for your SLI support HDMI ? You're just choosing a new PC, not writing a thesis - how much research should buying a computer take?
Less time spent agonizing over the technical features means more time to consider other aspects of a prospective purchase: Is the screen big enough? Are the mouse and keyboard of decent quality, or will you have to factor the cost of better ones into the purchase price? These are especially important in a laptop, if you're planning to actually use it as a laptop, because they don't lend themselves well to upgrading built-in components.
What kind of PC?
The first choice you'll need to make is: desktop or laptop?
Do you need to take your computer with you on the go? Do you want to put it on your actual lap while lounging on the sofa in your living room? Then you need a laptop. If a stationary PC is acceptable, you'll always get better bang-for-the-buck with a desktop - at any given price point, a desktop system will provide more speed and storage and a larger display than its portable competition, and will be more upgradable and expandable.
There's a bit of a trend right now toward "all in one" computers, with vendors like HP offering what is essentially a monitor with a computer built inside. My advice is to avoid these, as, in essence, they combine the worst features of a laptop with the worst features of a desktop. They may save a little space on your desk, but you'll pay a premium price for low mobility and limited expandability. If the monitor gets damaged, you have to replace the whole computer along with it. If the computer breaks, you have to replace the whole monitor along with it.
Sorting out the features
I've said that the technical specs of a modern PC aren't worth obsessing about. There is some value, though, in being familiar with a few of the terms that will help you to choose between systems in your price range.
First, a word about memory versus storage. As ingrained into our daily lives as computers have become, I'm surprised at how many people still don't understand this fundamental concept. Memory can be considered analogous to the grey matter in your brain - it's where the computer stores the information it's thinking about right now. Storage - usually in the physical form of a hard drive - is like the computer's own personal library. It's where the computer puts information it might need, but doesn't have to act on at this specific moment. When you put software on your computer, you need both the storage space to put it in and the memory to run it. Luckily, neither is much of a problem these days.
On to the terminology:
CPU Cores: In the past, most computers have been powered by a single processor chip as the "brain". It can do exactly one thing at a time, and perception of speed comes from the fact that it does that one thing so blindingly fast that it's moved on to the next ten thousand things in less than the blink of an eye. Modern chip manufacturing processes have allowed the inclusion of multiple processor "cores" so the hardware brain can do 2, 4, 6, 8, or more things at once. But just like when groups of people work together, there's overhead involved in keeping all those brains communicating - so two cores are faster than one but not twice as fast, four are faster than two but not by double, and so on.
Memory: Aim for at least 2 gigabytes (GB) of memory ("RAM") as an absolute minimum. Aim for 4 gigabytes: Windows is much happier that way. I multitask a lot - often with multiple applications running, a dozen or more browser tabs open, and a system-intensive game running to distract me from all that work I should be doing, so my main home PC has 8. Some ads will talk about "DDR" memory of various sorts and provide information about stats like "memory timing", but the dirty little secret is this: faster memory provides only incremental performance improvements. More memory is always better (and often less expensive) than faster memory.
USB 3 (etc): USB, or the Universal Serial Bus, has been around for a while now. It's how we connect our keyboards and mice, our thumb drives and external hard drives, and our phones and MP3 players to our PCs. Version 3 of the USB specification, the newest, is compatible with older potentially faster than its predecessors, but it's not widely supported yet. So while the earlier USB version 2 is a necessity (and it's impossible to find a new machine without it), USB 3 support isn't mandatory. It's a nice extra and provides a bit of future-proofing as more devices are gradually released that take advantage of it, but it shouldn't be an important factor in purchasing a PC today.
Solid State Drives (SSDs): Traditional hard drives are, in comparison to the speed of almost every other component in a modern computer, snails swimming through molasses carrying turtles on their backs. They're by no means slow at transferring information - but in a world of supersonic jets, the Ferrari to the airport becomes the bottleneck. The last few years have seen the advent of solid state drive technology - storage devices that have no moving parts like hard drives, but instead store information on chips more closely related to the memory inside your computer than to the spinning magnetic disks of yesteryear. (Does yesteryear even make sense in this marketplace? Yestersecond sounds more appropriate.) SSD drives offer a signficant performance boost and consume less power, but they're very expensive compared to normal hard drives. At this writing, the cheapest SSD I could find at Newegg cost $115. For $109, I can buy a one of the better-performing 500 gigabyte hard drives from the same site!) There's no doubt that a system equipped with an SSD will feel more responsive than one without, but be prepared to pay a premium - and if you're the type who needs a lot of storage space, be ready to invest in an external hard drive to plug into that USB port. (Luckily, those are cheap.)
Adding confusion to this issue is the availability of "hybrid" drives - traditional hard drives with some SSD-style memory attached. The drives try to watch what information your computer needs to access the most and copies that into the SSD storage while accessing the bulk of your data from the rotating hard drive. These represent a middle ground in price and performance. They haven't been widely adopted, but it's possible they might make their way into some consumer machines.
Touchscreens: Touchscreens are wonderful on phones and "pad" systems. For PC systems right now, they're expensive gimmicks with little support and bad ergonomics. Think about it - how much would you pay to be able to hold your arm out in front of you to drag your finger across a vertical screen so you can scroll through your family photos without using a mouse? Touch interfaces are no doubt a big part of the future of computing, but the current crop of touch screens just don't offer much advantage yet for general computing.
One last piece of advice
Once you've decided on a price range and narrowed your choices down to a few possibilities, the best thing you can do if at all possible is to spend a few minutes using the ones you're considering. Try to find them set up at electronics or office supply stores (where you'll sometimes be surprised by the competitive pricing vs. online retailers). Does the system respond quickly when you start up a program? Is the keyboard big enough to type comfortably and quickly on? Don't write off your overall sense of whether the machine you're sitting at is the one that "feels" right - because when all the technical details are put aside, that "feel" is going to guide your experience with that expensive toy once you get it out of the box.
After the purchase
In a companion article here on Infobarrel, I offer advice on getting the most out of your new PC.