One suggestion I keep hearing is to back away fron OS 9.2 unless you are using it under OS X. 9.1 has been better as far as stability on it's own aparently.

If it didn't come with the origional CDs, they will probably be hard to find now. Apple machines include machine specific CDs that do two things, either do a full reload like restore discs, or act as normal install discs and allow you full control. Check the fourms at macnn.com, otherwise, every copy of OS X comes with OS 9.2.

Sonnet, XLR8, and a few other companies do offer upgrades on processors.