Yes, given that you use the option to install OS 9 HDD drivers, and that you wish to use a (pre-OS X) OS that can 'see' files on a drive formatted in HFS+ rather than HFS. That means OS 9 or OS 8.1 and above. OS 8 to OS 9.1 will not run from within all versions of OS X in 'Classic Mode', but you may be able to boot into either or both of them (separately) to run older applications natively from partitions separate from the partition containing OS X. The pool is further muddied by considerations arising from the installed OS X version and processor, but a CRT iMac is unlikely to get into those leagues. Even a 700MHz CRT iMac should not be expected to leap over the Eiffel Tower.

By way of example, four 500MHz CRT iMacs of mine from 2000 to 2002 happily run OS X v10.4.11, boot into OS 9.2.2 directly as well as use OS 9 in Classic Mode/Environment, and can reboot happily from OS 9.2.2 to OS X. However, OS 9.1 quickly loses potency for booting as OS X rises from 10.2.8 to 10.3.9 to 10.4.11, as a result of both firmware and software changes, but the downloads for upgrade from 9.1 to 9.2.1/9.2.2 are still available from Apple. As an aside, as part of my use of Silverlining on every hard drive in my flock, those iMacs are formatted from Silverlining 6.5.8 under OS 9.2.2.

You will find useful reading at http://www.macmaps.com/macosxnative.html and

http://support.apple.com/kb/HT1395?viewlocale=en_US

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