If you're looking for a monitor to use as a second screen for your laptop, read on. John Carter gives this detailed account of how to get the best deal.
"You're looking for a monitor to use as a second screen for your laptop. You see a monitor or TV with a resolution of 1920 x 1080, or that it just says it has a 16 x 9 aspect ratio. How can you know it will be compatible with your laptop?
"Divide the smaller number into the larger number. The answer should be 1.777777778 for it to be a 16:9 ratio. Hence, the resolution should be 1920 x 1080 or 1280 x 720 for a 16:9 ratio. Your laptop has a 16 x 9 ratio and you want the monitor or TV ratio to be the same. Also check to see if the monitor or TV is 1080p or 1080i (see below). If your laptop max resolution is 1920 x 1080, you should have the display set on the laptop to that resolution when you are hooked up to a 1080p monitor or TV. 1080p TVs will convert any resolution image to 1080p, which is the only resolution that it can display at, so if your laptop doesn't have a 1920 x 1080 setting, pick the next lowest setting that gives a 16:9 ratio (widescreen).
"1080p equates to '1920 x 1080'. Another similar spec is 1080i which is the same as 1920 x 1080,but with a big difference in how moving objects are rendered. If you have a choice of monitors, DVD players, and TVs, get one with a 1080p spec. 'p' stands for 'progressive' and 'i' stands for 'interlaced'. Progressive gives a more accurate video representation of moving objects on the screen (interlaced tends to cause moving objects to smear), but some people will probably never notice the difference.
See this for a full discussion on progressive vs interlaced: http://www.axis.com/products/video/camera/progressive_scan.htm
And this for a discussion on TV resolution:
http://reviews.cnet.com/720p-vs-1080p-hdtv/?tag=rb_content;rb_mtx
"A 1080p monitor will cost more than a 1080i monitor. A 720p costs a little less, and of course a 720i costs less yet. If you are really unconcerned about video quality, 1080i or even 720i will work for you. However, you will never be disappointed with 1080p.
"Another major concern is the input to the monitor or TV. Your laptop has a dinky DVI connector (either a mini DVI or a micro DVI) and there isn't one monitor or TV that has anything like it. What is needed is an adapter. And you notice that there are several types of inputs on monitors and TVs. New monitors typically have DVI, VGA (aka, PC), S-Video, and maybe a composite input. New TVs typically have HDMI, VGA, S-Video, and maybe a composite input. Which adapter do you need?
"The output of the laptop is DVI. Hence, the logical adapter to use is the one for DVI if the monitor has a DVI input. If the TV doesn't have a DVI input (and it most likely won't) an HDMI adapter is probably the only choice, and it will work as good as a DVI adapter.
"Don't forget to determine exactly which type of DVI connector you have on your laptop and get the right adapter. If necessary, take you laptop with you when you go to buy the adapter.
"If your existing monitor or TV only has a VGA or S-Video input, keep this in mind: these formats are subject to video distortion and do not have the same high quality video available with DVI or HDMI."
That's a lot to digest, John, but some of our readers will really appreciate this info.