I have a iMac DV SE 400 with 256 RAM running 10.1. IE, SYST Prefs, AIM, Audion 2.6 and Mail takes 2 bounces and Address book takes 3. I got my 10.1 at around 7:30 at a CompuUSA store in Virginia. I went to the Apple Store around 12 to find out that 200 people started waiting in line at 7 A.M in front of the store (which is in a huge mall) to get a copy and the store ran out of copies in an hour. Luckily I went to CompUSA at night to find out there were about nine more available and went home happy! Hope the info helped.