Can you recommend a light weight Media Streaming server (software)?

Question by Life Explorer: Can you recommend a light weight Media Streaming server (software)?
I need a good lightweight media streaming server (software) for my HTPC? Can anyone recommend a good software package based on experience? It’ll be running on run on XP Media Edition 2005 on a Pentium 4 2.8ghz with 4gb RAM.
I can’t use Windows Media Center as it conflicts with SageTV which I use for my TV recording on my HTPC. So Win MC is entirely shut down.

I have TVersity running right now but it brings my machine to it’s knees. SLOOOW and degrading of my media throughput and quality. I can stream a movie but try a music video or concert and things go haywire. Run TVersity and watch my CPu utilization nearly max out…
So by lightweight I mean low processor load.

I was looking at XMBC, MythTV and PS3 media server. Does anyone have any recommendations?
I encode to mpg which my BluRay, XBox 360 and HDTV recognize. I also have a huge library of mp3s to stream. I may occasionally have an AVI, WMV (WMV9) or MP4 (DIVX, XVID, H.234) so transcoding would be nice but isn’t a necessity right now. I realize transcoding on the fly taxes the CPU and that may wait until a more powerful machine can be had. I’m hunting for a good upgrade to an good dual of quad core….

Can anyone make any recommendations? Based on experience? What machine configuration are you running?
12 hours ago – 4 days left to answer.
Additional Details
I need a software solution not a hardware solution. I ask about your hardware config so I can get an idea how you’re getting the performance difference.
Must be visible to DLNA certified clients, not just XBox.

Best answer:

Answer by TV guy
Windows Media Player has its own Media Server and you DON’T need to run WMC.

Start WMP and then enable Sharing to start the server..

What do you think? Answer below!