Earlier this spring I purchased a gigabit ethernet, G4, 400 MHz, 20 Gb HD. It does, indeed, have 4 ram slots. Mine came with OSX 10.3 Panther. I installed 4, 512Mb memory modules and the ASP recognized 2 Gb of ram and it runs lots faster than it did with Panther and only 384 Mb of ram. Although I own a family pack of Tiger, I'm leaving the Gigabit ethernet with Panther because of the following experience. I also have two G3 iBooks, a 700 Mhz, with an 80Gb HD, and an 800 Mhz, with a 30 Gb HD, both with 640Mb RAM. I upgraded the 700Mhz to OSX 10.4 Tiger and its performance slowed considerably. If I remember correctly, Tiger is a significantly larger system than Jaguar or Panther and seems to slow the older, slower systems down. (More memory might alleviate this problem, but that is not an option with these iBooks - they are both maxed on RAM). I'm planning to move it back to Panther because of this. That is, of course, unless some to the guys with more experience than me tell me I'm wrong and what I did to slow down my iBook besides upgrading to Tiger. Hope this helps. Dan