Since they're on separate drives, you should be in good shape although it's unusual for an OS X disk not to show up in the "Startup Disk" control panel in OS 9. Does your OS X disk show up on the desktop? If not, you really should investigate that-offhand, it could be something simple like a loose ribbon cable, your ribbon cable could be bad, or the drive may have died.
In any case, the easy route that works on some Macs is to hold down "X" while powering on the computer. That doesn't work on everything, but on computers where it does work it will boot OS X. This is handy when you are dual booting off the same partition.
Since you have two separate drives, you can also bring up Boot Picker assuming that the computer is new enough to have it(the form we know now, that persists to current Macs, came into being with AGP-based Macs-that means the Sawtooth, Pismo, and newer). To access this, you hold down "Option" while powering on the computer. In PPC Macs, it will bring up a blue screen that will then show each bootable volume as a tile that you can click on. Once selected, you tell the computer to boot off it.
