Well I was trying to decide between the older 2.0 and newer 2.3, but now it's between the 2.3 or the 2.5 in the sale section of apples site. I have read posts between the two, but I am not satisfied with the responses, so maybe I can get some better help. I read that the 2.3 was faster because of the hard drive, so if I upgrade the HD in the 2.5, it will be faster correct? I plan on putting 2.5 gb of ram in whichever model I choose. Someone mentioned that is where the big difference will be noticable between the 2 systems. Does the 2.5 on the sale site come with tiger installed? and I thought I read that the 2.5 is liquid cooled, which sounds right, but I thought that the 2.3 was too? Can I later add the 16x superdrive to the 2.5? Also, does the 2.5 have pci-x slots like the 2.3. I plan on ordering probably tomorrow, so I am trying to get all of these answered. I guess it comes down to: will i notice any speed difference in the two models if I put in 2.5 gigs of ram, and a 250 gig hd? Sorry for all the questions, I just want to spend my money wisely. Thanks!