What kind of video card and tv do you have? I'm lucky in that my video card (NVidia GEForce4 MX 420) has an S-Video output, and my tv has an S-Video input, so I just needed an S-Video cable and then had to fiddle with the video card settings to get it to output. Depending what inputs your tv can accept, that will most likely dictate what kind of video card, if any, you will need.
Is your TV is an HDTV? Are you planning to use your TV and monitor at the same time? For regular TVs:
You need to know what kind of computer you have. Dell? Compaq? Self-built? If you don't have the manual with you, find the computer make and model by right-click on the My Computer icon, then selecting properties. If you have the information, enter it in Google or your favorite search engine and look up the specs for it. Look especially for any mention of Accelerated Graphics Port (AGP) or PCI-express (PCIe) slot; if either are present you can use a video card that uses either interface. Otherwise check for any available extra PCI (NOT PCI-express) slots. This will determine what kind of video card you need.
Next, you'd need a video card with something called "TV out," which is a RCA/Phono jack or S-Video jack with S-Video-to-RCA converter. Maybe you already have it but haven't looked. Most recent video cards would have this included. They can extremely cheap if you're just planning on watching TV and nothing demanding like "hard-core" gaming. I would warn that TV out will likely output a low resolution since non-HD capable TVs lack the high resolutions computer monitors have. I prefer online-shopping to brick-and-mortar stores because of pricing.
For audio you'd need a mini-stereo to RCA cable. They can be found at any mega-mart type store or Radio Shack. The mini-stereo end connects to your sound card on the back of your computer and the RCA ends connect to your receiver, VCR, etc.
Connecting video is the first part, but you are probably going to want to route audio as well.
Depending on the TV you have, I would recommend picking up a media switch. I picked one up a Kmart for about $30. Mine sucks, but does the job. Basically, it allows you to route your DVD, VCR, videogames, and cable/satellite (or in your case, Internet TV), to various components.
So for example, my TV came with only one video input. With the switch, I can run multiple devices into my TV without having to repatch everytime. I can also run the audio of my Playstation 2, DVD Player, and VCR to the auxillary input of my stereo (much better sound quality than my television speakers).
Some of those switches can deal with S-Video/RCA Video problem.
Of course, if your TV has enough inputs to handle all of that, then you can pretty much ignore this post.
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This is a pain to do well, just so you know. I'm a computer guy, and I gave up and bought a TiVo. It was going to cost me about the same amount to do it, and the video quality never looked as good to me as a TiVo does.
If you are talking about using a sytem you already own, the most important bit is the video card. Make sure you have one that will go to TV if the monitor is not connected. The first card I ever did this with had that feature (it was an old Monster card back before they went out of business) but the second had to be turned on from the video settings - something that would have been easy enough to do had there been a monitor nearby (I was going to use the TV!).
I would recommend skipping this for now, and looking to buy a computer with a media center OS at the next round of computer purchases you make. TiVo is pretty cheap ($49-$69 after rebates) so if you are just looking to do an HTPC for time shifting programs, I'd go that route. If you are looking to do MAME and all that then maybe this is worth it.
In my experience text was almost always unreadable on my 32" TV due to interlacing, even at the lowest resolution settings for my video card.
I just bought a Mac Mini, and I've found it painlessly easy to turn it into a Media Center PC-especially once I downloaded and installed Apple's Front Row program. All I need to do now is add a USB IR remote to the system, and I'm set.
Right now, I have an old PC in the living room that's being used to stream music from mine and my roommate's PCs, but I've found trying to stream video woefully inadequate. I'd like to be able to stream the video from the Mac in my bedroom to the PC in my living room. Is there a quick an easy solution for this? I'm wondering if it's just a matter of not having enough RAM installed in the computer itself, or if trying do stream video over a wireless network is just a waste of time.
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I assume this is Windows XP. If so, try Tweak UI. It's one of Microsoft's PowerToys that lets you adjust a few specialized settings. You can adjust the Logon and AutoLogon settings, and that will probably fix it for you.