Use your TV as a computer monitor: Everything you need to know
Bigger is better, you know, and this way I wouldn't have to drop a couple hundred bucks on a new piece of equipment. But just because HDTVs look a heck of a lot like computer monitors doesn't necessarily mean they can replace computer monitors. Or does it Here's what you need to know if you're thinking about sticking an HDTV on your desk.
Will it even work
The short answer: Yes, although you may need a special cable depending on what type of input/output ports you're working with.
All modern HDTVs have HDMI inputs--some older HDTVs have DVI inputs instead--and some have VGA inputs for "PC use." If your graphics card has an HDMI output, you're good to go: Just use an HDMI cable to connect your PC to your HDTV. If your graphics card only has DVI outputs, I suggest snagging a cheap HDMI-to-DVI cable and plugging it into your HDTV's HDMI input. Although some HDTVs (and some graphics cards) have VGA inputs/outputs, this is not the ideal choice--it's an analog signal that will give you a far fuzzier, lower-resolution image than an HDMI or DVI signal.
If you're setting up your HDTV as a second or third monitor, you may need to use your PC's DisplayPort output, in which case you can purchase a DisplayPort to HDMI converter and plug into your HDTV's HDMI input. The main difference between HDMI and other digital signals is that HDMI carries sound as well as video--if you use DVI or VGA, you'll need to connect your PC's sound to the HDTV (or to external speakers) separately. (DisplayPort also carries audio signals.)
Before you start using your HDTV as a monitor, you need to figure out whether your graphics card/integrated graphics is capable of outputting at the resolution of the HDTV. To do this, you'll first need to find the resolution of the HDTV by consulting the manufacturer's manual. Be aware that some HDTVs have non-standard resolutions. Then, find your graphics card's maximum resolution by going to Control Panel > Display > Change display settings > Advanced settings > List All Modes. Find the resolution that matches your HDTV and select it.
Will it look good
Maybe, but this depends on a number of factors, including what you want to use your HDTV monitor for. Most reasonably-priced HDTVs top out at 1080p, or 1920-by-1080 pixel resolution. On a 15.6-inch laptop screen, the Windows desktop at 1080p looks pretty darn good from a couple of feet away. On a 32-inch HDTV screen...not so much.
What's important here is pixel density, or the number of pixels packed into one square inch of the screen. A 15.6-inch laptop screen has the same number of pixels as the 32-inch HDTV screen, but the laptop has a much higher pixel density (141.21ppi) than does the HDTV (68.84ppi). Thus, the laptop's screen will appear clearer, sharper, and more detailed than the HDTV's screen when viewed from the same distance. The importance of pixel density decreases with viewing distance; that's why the iPhone's "Retina" screen has a density of 326ppi, while the MacBook Pro's "Retina" screen has a density of just 227ppi.
What this means for you is that a larger but less pixel-dense HDTV screen will display text, icons, and images as blurry and difficult to read if you're sitting a normal viewing distance--a couple of feet--away from your computer.
If you plan on using your HDTV monitor to do anything other than watch Netflix or play games, you'll ideally need to find use an HDTV with a higher pixel density (I like to shoot for at least 80ppi, which means no larger than a 27-inch screen at 1080p) for comfortable viewing. Or just hang it on the wall rather than plopping it on your desk.
Speaking of gaming, if you want to use your HDTV monitor to play games, there's another factor you'll need to take into consideration: Input lag.
Input lag is the delay between movement you make on your input device (in this case, your mouse) and what displays on your screen. While many computer monitors prioritize minimal lag times, many HDTVs do not, and prioritize (laggy) video processing instead. But those extra milliseconds will definitely make a difference when you're playing a high-stakes FPS.
DisplayLag has a pretty good database of input lag times that you can sort by display type--you want to pick an HDTV with a lag time of no more than about 40 seconds. If you run into input lag problems while gaming, try activating your HDTV's "Game mode" setting if one is available.
Is it worth it
If you're looking to get the best bang for your buck, an HDTV isn't necessarily going to save you money over a monitor. In fact, if you're purchasing a new display, I recommend sticking with the tried-and-true computer monitor. For one thing, smaller, cheaper HDTVs are typically 720p resolution, not 1080p, while similarly-priced monitors will almost always be 1080p. So if you're looking for something under 27 inches, an HDTV will probably be more expensive and lower-resolution.
If you're looking for something larger than 27 inches, remember that pixel density decreases significantly with every few inches you gain, and there's a reason HDTV-makers suggest sitting several feet away from their creations. If you need a display that will multi-task as an up-close work/email display as well as movie/entertainment display, you'll want something with a high enough pixel density that text won't be a pain to read.
There is an ideal situation in which the HDTV-as-monitor shines, though.
If you want to add an extra display to a single- or multi-display setup for entertainment--say, so you can watch Netflix or Twitter while you write articles, or so you can play Skyrim on a 60-inch screen--then an HDTV can be a very capable (and cool!) monitor replacement. Bonus points if you happen to have an extra HDTV lying around, or if you can pick one up for dirt-cheap.