Hauppauge Media MVP

$99 but sometimes can be found for cheaper with rebates

http://www.hauppauge.com/html/mediamvp_datasheet.htm
http://www.hauppauge.com/pages/support_mediamvp.html

great site for mvp and pvr250 products. check out the forums. Get the latest beta drivers from here too:
http://www.shspvr.com/

this is the alternative ui that I use:
http://sourceforge.net/projects/mvpbtv/
but then I hacked that and modified it a bit.

- tiny box, no fans
- plays mp3, jpg, mpeg1/2/4/divx/xvid, shoutcast internet radio. Basically now I can watch all my "tivo/rcepg" recordings in the bedroom.
- wired ethernet port. You can use a wireless bridge if you want. You will need 802.11g if you plan to stream mpeg2.
- easy html based interface that you can hack. I've added the ability to check weather and local traffic maps.
- One pc must be on that runs the service. Very easy to add directories that are available to the mvp. Even network shares work fine.
- Good play back controls, resume even after power off on multiple files, quick 30 sec skip forward/backward to skip those commercials, instant jump from 0-100% in 10% increments using the number keys!
- picture quality is excellent.
- the box runs linux and boots the entire os off an image file on the host pc so upgrades are easy! Source is available so people have been hacking it and adding stuff like telnet.
http://www.shspvr.com/mediamvp_apps.html
- UI uses internet explorer object to render the html that makes up the UI. Control from the mvp to the host pc service is done through a modified version of VNC. Actual streaming of media is proprietary (NOT VNC).
- you can add up to 12 of these things on a single network.
- some small stability issues but it works fine 95% of the time. But then again I am using the beta version of the software.
- beware hardware revision D3 (d3a is fine). I hear those are defective. I have a D1 and it's fine.
- the perfect companion to any HTPC/home grown Tivo setup.
- doesn't playback HDTV streams.

Cheap, quiet, near instant on, plays everything, great picture quality, open, hackable, expandable. It's nearly perfect if you don't need HDTV capabilities.