i thought i would chime in with my QS - i have two of them now. got them a year ago and that was my first entry into this kind of mac. id had a performa as a kid but once windows 98 hit; i was a PC kid.
so i have a 800mhz QS that came with an 8500 and 4 scsi drives. i havent used any aftermarket 3rd party stuff to upgrade it with because of all the cost involved there so i just modified existing mac/PC hardware.
so i ended up with a Dual 1.4Ghz, 150Mhz FSB, upgraded to 3MB L3 cache, 512GB SSD, blueray drive, X850XTPE, and 1.5gb 150mhz SDRAM. i run 9.2.2, 10.4.12, 10.5.9. mostly os 10.5 and 9 is what i use. i keep a 9200 PCI radeon in there too for OS9 games that i want to play. the X850 does about as well as a rage 128 wtih no drivers.
my second 933QS is stuffed into a Performa 6300CD case. it runs a 1.42Ghz single core, 150Mhz FSB, ti4600, 1.5GB 150mhz SDRAM, 256GB SSD, and blueray drive.
i keep both of these on my network where i have most of MR and MG downloaded as well as all my physical MacAddict CD's ripped to - so i run/install what ever from a 150TB NAS over the network.
at some point i plan to stream OBS to YT with this setup.