There seems to be a bewildering array of devices that do this, plus a million other things. I’m not really interested in the million other things, at least, not if they cost extra. What I really want is something I can hook up to my TV, connect wirelessly to my home network, and access my library of videos that live on the PC from some sort of interface on the TV. Is there an inexpensive solution to accomplish this?
Define “inexpensive”. It’s a very relative term.
Fair enough. $100 or less?
Do you have an existing computer you could use?
I don’t have cable, I just have a computer hooked up to the TV with a single s-video cable. It’s got a wireless internet card, and an old 5.1 speaker system (the center channel is hooked up to the TV). I have an ATI video card and that is compatible with the ATI Remote Wonder, which is what I use as my remote. ATI cards come with their multimedia player stuff, but I don’t use that I just use Windows Media Player (and Netflix Watch Instantly, and Amazon’s movie service, and YouTube).
I can’t say how much all this has cost me because I’ve pieced this together over several years. If you have an existing computer you can use, you can set up Linux and MythTV. What sort of hardware you already have will determine how much more you need to spend to get all the right components to do what you want.
At <=$100, you’re pretty much going to need to already have a computer with wireless, I think.
TV-out (s-video) and HDMI-out video cards can be had in that price range, but I’m not aware of any set-top-box-type device that can do that for that little money.
Consider shopping TigerDirect.com’s off lease computers, which you can sometimes find with WindowsXP Media Center installed. OEM MediaCenter computers are supposed to come with TV input and output already built in. so you should only have to buy a wi-fi card extra.
Don’t know your set up, but what worked for me was just to move the computer over to the entertainment center, hook it up directly to the flatscreen with DVI, get a wireless keyboard and mouse, and use the computer from the couch.
Cost me $30 for the keyboard and mouse, and $0 for unlimited Netflix streaming and whatever else. (no extra devices like that $99 Netflix box or Pandora Box)
For a slightly more expensive version, the Xbox 360 is honestly going to be your best bet (if $220 is within your price range). $199 gets you a 360, $20 gets you a dedicated wireless router (you can get regular routers to function as a wifi adapter for the 360 now, instead of spending $99 for their branded peripheral). Its DVD player isn’t great, but passable if you don’t want something that big in your cabinet that only does streaming.
Edit: Unless someone can put together a $200 media center home theater solution for you. Because I think that might have more functionality. (And something I might think about as well.)
Edit 2: JSexton - you said you have a “library of videos” on your PC. What are they? I don’t have a single video on my harddrive, and I have no idea what people might be watching and saving. Is it home video? Ripped DVDs? Something I’ve never seen before?
In that price range the only thing I know about is the Western Digital TV box. I think it’s in the $99 range. It won’t let you stream from your computer, but you can put all your video files on an external usb drive and use this to serve them up to a TV. Last I looked at it, it had a wide variety of supported video formats.
I personally use an Apple TV it’s more expensive (starting around $240 or so) and a bit more complex to set up (requires a computer running iTunes to connect to). But the interface is much easier to use. Which let’s me answer your question Munch. I originally started looking for media streaming options after buying my 3rd Little Mermaid DVD. My 4 year old loves to feel like she’s putting her own movies on, but hasn’t really grasped the concept of not scratching the hell out of them. I tried the wireless keyboard and mouse routine, and just didn’t like it. It was still too cluncky for everyone in the family to easily use. The apple tv solves that issue. My daughter can scroll through her movies and pick what she wants to watch and start it on her own. Think of it like a Tivo for all your movies. Every single one available at the click of a button. It remembers where you are in a movie, so if you stop watching, you can pick up where you left off at any time. Which is a god-send for me because it seems like I have to watch any of my movies in 15minute segments spread out over 4 or 5 days. So I have something like 700 movies loaded on a NAS drive and about 20 TV series there as well.
Dude, seriously? No idea? 
I can get an old slimline PC from work for nearly free. Maybe a wifi card and TV card on that are my best bet. My main PC has a built in DVR, so I’m recording TV shows to it. That’s one of the main things I want to stream. I also have ripped DVDs and .avi files to watch. It’s not porn, but I’m surprised that that option didn’t occur to you. 
Thanks, folks.
I will admit it didn’t occur to me, but who saves that stuff? It’s all over the internet for free and easily accessible. I have better harddrive allocation needs! 
FYI: Here’s a refurbed 360 for $150:
http://news.cnet.com/8301-13845_3-10291671-58.html?part=rss&tag=feed&subj=TheCheapskate
Heck, an old X BOX will work (not 360).
The cheapest and most flexible route is, as people have said, to just hook up your PC to your TV. But if that’s not convenient, and you’re looking for a dedicated device to do streaming, then one relatively cheap option is the Kodak HD Theatre. [Big Disclaimer: I don’t work for Kodak, but I was involved in the development of this device.]
It’s going for $170 on Amazon. The main advantage of this over hooking up a PC is the user interface; it’s designed to be used from across the room, so it’s pretty easy to navigate around your movies to do what you want to do.
How’s $107? Doesn’t look like it’ll connect to your existing network, though.
If you have access to a near free PC then, yes, that would be your best bet.
I would suggest you load it up with windows 7 RC which is free to use until this time next year. you cna worry about buying license then or going back to XP/vista. the media center functionality on Windows 7 is nothing short of brilliant.
The problem with using the xbox 360 as an extender is that it’s loud. My Home theater PC is quieter and it has a decent mid-range video card (I also play sports games/racing games on it) and a 3 core Athlon CPU. And it’s QUIETER. So depending on your living room setup a silent PC might work better for you.
My Home Theater PC has Windows 7 beta and two tuners for a total of 2 digital and 4 analog channels. It’s hoked up to my network so I can watch streaming shows form Netflix, downloaded episodes I’ve missed, ripped DVD’s etc. It’s a lot more flexible than a set top gadget, but if you’re building from scratch, is usually more expensive as well.