What can you do to get better SNR margin which means of course no lag/jumpy video on airplay form you mac to AppleTV. You can use a router that has 5Ghz instead of 'the normal 2.4GHz'-5GHz is faster with a good signal, but 2,4GHz will go through walls better. There are plenty of graphics cards out there that are spectacular for video editing; you don't have to have the best one to achieve amazing performance. I assume you have a customizable PC (and not a Mac) since you're asking a question like this.

A video card can (not always) somewhat improve video quality. However, video quality ultimately depends on how well the video was encoded. If it was encoded with low bitrate and / or poor settings then the result will be 'bad video'.

The only real way to improve the video is to re-encode the video with higher bitrate and better encoding settings. Other things that can affect the quality of the displayed video are: 1. The quality of TV or LCD monitor. Basically the display panel itself where it's LCD or plasma. Quality of the connection.

Meaning good quality cable and input and output ports. Video card to a limited degree.

None of the above will improve the quality of a poorly encoded video.

At one time the idea of watching movies on a Mac seemed both quaint and inconvenient. After all, you already had a TV and its accouterments in the rumpus room. Why gather friends and family around the desk in the corner of the living room to watch movies on a 17-inch iMac? But times are changing.

A home media center is no longer a crazy idea. Nor would anyone look askance if you moved into that same rumpus room and devoted some of its time to entertainment. Once you accept the notion of a Mac as a home media player, your next thoughts naturally turn to movies and, likely, the iTunes Store. But the Store isn’t the end-all-and-be all of online movie sources. Although outfits such as and demand that their content be watched on devices that don’t bear the Apple brand, there are a handful of other sources for movies that you can play on your Mac.

Step up to the ticket booth and check out these options. The iTunes Store We can hardly begin without mentioning what the iTunes Store provides. Of any source, the iTunes Store is the most Mac friendly.

Offering thousands of movies for purchase or rental, the Store’s movies are playable on a Mac, Windows PC, Apple TV, iPod, and iPhone. You can transfer them to and play them on any computer authorized with the Apple ID used to purchase or rent the movie. The Store sells and rents both standard definition and HD movies.

There are currently more than 280 HD movies, available in the 720p (1280 by 720) format. Many feature 5.1 surround-sound soundtracks as well. Apple's prices are based on a movie's age and format. Apple characterizes movies as being library (meaning older) or new. Prices generally shake out as follow: standard-definition library titles cost $10 to purchase; new standard-definition titles are $15; all HD titles cost $20; iTunes Extras movies, which contain bonus DVD-like material, cost $15 in SD format or $20 in HD (there are some exceptions to iTunes Extras pricing, however). ITunes StoreAs for rentals, standard-definition library titles cost $3, and new library titles in standard definition cost $4.

Library HD rentals cost $4, and new HD rentals cost $5 (iTunes Extras content is not available for rentals). After you download a rental movie, you have 30 days to watch it. After you start watching it, you have 24 hours to finish it; the movie is automatically removed from you Mac after that period. During those 24 hours, you can watch the movie as many times as you like. Like all videos sold at the Store, you can't burn movies in a form playable on a DVD player. You can, however, burn purchased movies as data for backup purposes. Amazon Video On Demand is one of the few movie services other than the iTunes Store that’s not actively hostile to the Mac.

It can afford to be magnanimous because it streams movies via a Web browser, even one that sits on your Mac. You can also watch the service’s movies on TiVo, Roku players, compatible Sony Bravia devices, Panasonic TVs that support Viera Cast, and compatible Samsung HDTVs.

You’re allowed to download videos to up to two compatible devices—a TiVo and Windows PC, for example. Regrettably a Mac isn’t one of those compatible devices. Clearly, Amazon Video On Demand is not the ideal service for Mac users, but it does offer a couple of advantages over the iTunes Store. For one, if you purchase a movie it's accessible to stream on any Internet-connected computer, so can watch it on your laptop while visiting the in-laws without having to remember to copy it to that Mac's hard drive. Another—particularly if you're willing to broaden your video diet to include TV shows—is price. Amazon, like the iTunes Store, sells individual TV episodes for $2 (SD) and $3 (HD).