I believe that WMP9 is going to kill WMP6.4 or 7.x when you install.
However, there is a sort of "classic" media player that is part of 7.x and 9.x, try start | run | mplayer2.exe to see it. It will have access to all the codecs which 9.x sees.
As to the player object, WMP9 will emulate player 7.x when embedded in a web page with the WMP7 classid (ends in e95), as well as being callable with its own classid (ends in faa6).