Basically I have a bunch of AVI's and such sitting around. In the past I've used an svideo/5mm [computer side] to RCA [TV side] wire that basically makes the TV act as a monitor and uses the TV as speakers. Wondering if there's a better way. Like my question mentions I'm most interested in wireless solutions.
Try the Apple TV. It can stream your music, photos and movies from any iTunes computer on your network to your TV.
If you find the Apple TV software limiting, you can always install 3rd party applications on it, such as XBMC or Boxee. Lifehacker has an excellent article on getting Boxee up and running on your Apple TV:
Boxee's media center gives you that, and all from one application. It's free, it's open source, it's built from the guts of the killer Xbox Media Center (which is still a quite active project itself), and it simply works. Loaded onto an Apple TV, or any TV-connected computer, Boxee also gives you free license to drop your cable or satellite dependency with hardly any regret, especially once you realize your year-to-year savings.
Personally, I think Boxee makes an Apple TV worth every penny. With it, you can stream videos and movies from multiple online providers, play virtually any media file regardless of codec, automatic torrent support. It even has reviews and Last.fm music recommendations.
I use an Acer Aspire Revo with Ubuntu and XBMC. This allows me to stream from my NAS, use the internal hard drive, or a USB key/SD card.
The GeForce 9400 graphics card can comfortably handle 1080p which I understand the Apple TV struggles with. I've detailed how to install Karmic Koala (Ubuntu 9.10) and XBMC on the Revo on my website.
I've also set up the Revo as a Squeezebox server as its power consumption is low and it is very quiet.
Original Xbox with XBMC works great, since you can install a large IDE hard disk and hook it up to your network and will probably be cheaper than the Apple TV.
Not sure if you can get Boxee running on it though. Edit: No it won't since Boxee supports HD and Flash, which the Xbox won't, plus it would be a touchy subject...
If you own a HD-TV the Apple TV will be better for streaming HD-content and it looks waaay better.
Plex (http://www.plexapp.com/) is the simplest media server out there right now. You run "Plex Media Server" on any device you want to stream media from, and run the actual "Plex" application on the computer connected to the TV. The server and actual application can run on the same computer. Plex can even stream from the server to a mobile device (iPad, etc...) with their Plex app. Additionally, Plex has lots of add-ons that are incredibly easy to install so you can watch Netflix, Amazon Video, Hulu Plus, The Daily Show, and The Colbert Report (among lots of other services) right from Plex. Quality is awesome and the software looks great and is super responsive, even on an older computer.
You could use a 'Media Extender' like an Xbox or PS3 to stream to.
PlayOn will transcode videos from almost any format from a Windows PC to an Xbox 360, Playstation 3, Nintendo Wii, and many other DLNA network devices. However, if your videos are already of the proper format (DivX for one) an Xbox 360 or Playstation 3 will already stream them using Windows Media Player.
Without knowing what you have, it's difficult to specify; as some TVs support this "out of the box", and come with their own network port on the back.