Just an update to this:

All up and running with a dual boot setup of 9.2.2 on a 9GB partition and OSX Leopard 10.5.8 on a 60GB partition. Both OS's run really nicely - Leopard is not too sluggish and, with OS 9 as its own beast, I don't miss the Classic option of 10.4.11. That 'option key' boot OS selection is really handy.

I added a micro USB wifi 'n' adapter (an EDUP N-8505GS) which runs fine under OSX and allows me to connect to WPA2 wireless 'n' networks. Sweet. New battery on the way from the bay too.

Thanks to my other Macs and my Hackintosh, I've now got System 6 through 10.8.3 covered