Ram useage
People have a lot of complaints about not enough RAM, I've used OSX (10.0.4 public) on a number of systems this is how I rated them (my patience is pretty high for OSX)
iMac 233 G3: 96MB Ram: Too slow to use, blame it on the ATi I think, hardly useable, classic is worthless. 3.5
Powerbook 266Mhz G3: 64MB Ram: runs, keep to small apps, and one at a time. 6.0
AIO G3 266Mhz: 128MB Ram: This was my brother's computer, it ran OSX OK (Public Beta), but it was too slow for him, some people may find this config entry-level OK. 7.5
iBook Dual USB G3 500: 256MB Ram: This is my new laptop, I run OSX 10.0.4 on it all the time, it sleeps well, wakes up fast and runs quite quick. Truly useable in almost all cases. 8.0
PowerMac G4: 256MB Ram: Running w/256 the System Controlls open in 4 bounces. 8.5
PowerMac G4: 512MB Ram: I got an upgrade, now it opens in 2 bounces (hmm 2x Ram=2x performance holy sh**) 100% useable, except now I need software base station for the iBook, damn. Runs classic lighting fast, Finder is slower than I'd like, window resizing sucks, but those are all unavoidable. 9.5
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Running under Puma (10.1 public release) I THINK all the systems will be able to handle OSX, the imac will be useable, along with the powerbook. The AIO and iBook will become really quick OSX boxes, and my G4 will finally be able to kick the crap outta my freind's 1.0Ghz AMD in Photoshop.... (my other freind has a 1.12 AMD and that'll be more tricky to beat, hmm maybe a new DIMM)