I'm running Poser4 Pro pack. What is the highest quality render? File size does not matter, I'm looking for the best quality.

May seem obvious, but best quality for what? "Quality" must be gauged to output medium, i.e. print, video, web, etc. Then, within each media, there are sub-issues related to intermediate production processes and equipment. That blah-blah said, just render that sucker as big as you can & save in a lossless compression format and then scale down to fit later.

I must be losing my mind. I could have sworn I put something in there about rendering an animation file. :) Anyway, I'm looking to render an animation. Which codec is the best?

Getting closer! Video, Film, or Web? Generaly, if going to pro video or film, don't use any codec. Output individual frames and let your post or transfer house compile the animation directly to the format in which your program will be mastered. For the net, you'd need to define your bandwith target. (gotta run now -- hopefully the next billygoat to come along will pickup the quest for quality)

Ok, let me bore you with the details. I have a 60 second animation that will play on a projection system. The animation will run on a PC and be projected onto a large white screen. The resolution of the projector is 640x480 with 24 bit true color. So, the file will be saved and played as an AVI. Is there a better format for this type of display than AVI? Which codec (if any) should be used that will give me the best quality? The size of the file is not relevant. I plan to burn the file to a CD for transport.

As you'll only have 650MB or so worth of storage on a CD, I can't recommend saving the video as uncompressed video, because sixty seconds of raw video at 640x480x24 would take up multiple CDs. Also, some PC systems don't have enough horsepower to handle playing back a bitstream that large in real-time.

You're best off using either a lossless codec with perfect image quality (like Huffyuv), or a lossy codec like DivX (set to minimum compression for maximum image quality).

I tested various codecs (including Huffy) in Poser a couple of months ago. Read about it in the Director's Cut forum:

http://www.renderosity.com/messages.ez?ForumID=12425&Form.ShowMessage=920863