For pretty much universal PC playback MPEG-1 is the way to go. Nearly every computer still alive will play it and it will scale pretty good. If you have Compressor 2.0 it will make MPEG-1 clips. Cleaner is ok too. I shoot for around 3000kbps and make the movies 480 x 360. In cleaner you can crop the sides a bit which will help the overall image. If you use cleaner also slightly add some brightness and perhaps some saturation.
Windows Media is ok, but you’ll need Flip4Mac (not a bad purchase) to export Windows Media 9 clips directly from the timeline. For those I use 640 x 480 and go max quality 2 pass VBR.
Still MPEG-1 will allow everyone to view the files, they will play on slower PCs and will scale to full screen pretty well. Windows Media might give you a better looking file but does require you to be able to export to WMV out of FCP ($179 for the Flip4Mac Pro package).
Stay away from Quicktime…too many PC users will not have it and you will get nothing but complaints that the movies you provided will not play on their computers.
Rich Rubasch
Tilt Media