I too use these other players from time to time because there are no Quicktime streams for certain audio and video sources. I understand that Windoms Media Player for OS X is supposed to be out sometime around now. At least that was the original statement by Microsoft.
Realplayer is a different story. I understand that Realaudio is going to make a new combination player. I have read nothing about a Mac version. Perhaps someone with more knowledge can enlighten us.
I know that Realplayer produces some Unix flavors of Realplayer. Any Unixheads that can tell us if there is a OS(uni)X version being contemplated or engineered from these other flavors?