Admittedly a novice compared to the gurus on this forum, but i use (and love) sorenson squeeze and although initially used .rm files as i personally think they give the best output for lower bandwidth quality and copmparable to the others for higher, i have now been converted to flash. The file sizes are a bit bigger (although that could be just my inexperience) but the streaming is great and after finding a free flash player which is simple elegent and effective I am a happy man.
if you want to have a look: www.youth-tv.co.uk
The video on the home page is encoded for about 110kbps, clicking on one of the videos links will give you options of looking at a file encoded for about 400kbps and screened at 460 x 320px
PS: a big thanks to this forum for all the pointers and threads which led me to squeeze and flash. as ever this board is fantastic.