It can be done, you just need something like at least 1.5MB per second internet connection and a way to connect between your computer and your TV. What type of TV are you connecting to, a large HD?

You need to check what type of connection[s] are available and what cables you will need to connect between your computer to your TV [HDMI connection, S-Video connection, a VGA connection or a DVI connection]. Long runs of cables, in general, means some degree of signal quality loss.

If you don't have compatable connectors or possible cable configurations, then you might want to look at buying or using a game console or stand alone media box. Some specific boxes [gaming consoles XBox or PS3 and media boxes like Netflix and Roku], media centers and wireless media routers will do what you want, also. It may make sense to go this route rather than tie up your computer, especially if you are going to have to upgrade a graphics card and RAM on an older computer. Or upgrade to handle a large Hard drive to store and play back recorded video.

Once you got your computer hooked up, ready to send to your tv, I higly recommend the Boxee software to browse the videos and sounds on the web. It is designed with watching from a distance in mind and has all kinds of apps for you to install and enjoy your favorite (online) media. Best of all: it's free and open source! check www.boxee.tv

No mention of what hardware you are starting with. The key question is whether you are dedicating a computer to your TV or whether your 'regular' machine is going to do double duty. Assuming you have a reasonably recent flat panel TV, DVI to HDMI cable gets me the best results for video. If the panel has VGA then that is an option although not as good quality IMHO. The next option (as suggested above) is a dedicated box of some type (XBOX, PS3) but typically requires some hacking to get access to all sources of content, which is why I prefer a regular computer. Then the question is where are you going to get your content. In Canada, there are some limitations. Sites like Hulu aren't readily available on this side of the border. So if you really want "live TV" you will be likely going to regular websites and watching their webstreaming content.

Resources Life Hacker Media Centers Building a Boxee Media Center Connecting PC to TV (youtube)

Does your PC currently have a secondary video out? Is it a proper dual-head, with a 2nd VGA (or even DVI or HDMI), or a lesser-quality S-VHS (aka S-video) or Composite (yellow RCA) output?

There are VGA extenders that will let you use ethernet/Cat5 cable to run through walls and across distances - here's one, but I've seen cheaper on eBay. I think the distance is less of an issue with the RCA or S-VHS cables, but they'll max out too (S-vid apparently at 150ft, but apparently there's a Cat5 adapter for it too.

uses Mozilla firefox install the TV-fox add-on, hook the HDMI connection from the computer to the TV, pick that as your input on the TV remote, watch!, wireless internet may be helpful if your internet line and tv are not close together.