Eek, sorry about that.
If you want to use your old OS 9 Applications through OS X you would use the Classic mode within OS X. This mode effectively runs both OS's simultaineously in a similar way to when you run a PC emulator on the mac.
You don't need to partition your drive to use this mode, simply have a version of OS 9 instaled somewhere on your hard drive (I partitioned my drive because my switch over to OS X was slow and that way it was easy to boot directly from OS 9 and keep everything seperate + I went through a bit of a partitioning phase)
You can set Classic to launch on start up or launch it from the systems preferences folder whenever you like. It will also start if you try to open an OS 9 App.
Sorry if I confused you, but it'll all make sense once you try it out
the point is that it really is a piece of piss.