AFNI and SUMA run on OS X. There are no particular issues, at least since the release of OS X 10.2.5 and Apple's X11 beta version 3.
With the recent upgrade in the video drivers in OS X 10.2.5, SUMA renders 3 frames per sec on my iMac, which is fairly interactive (rendering 200,000+ triangles per frame). One advantage of the OS X platform over Linux is that the OS directly supports the nVidia graphics, which makes installation of SUMA much easier. One downside is that the Linux drivers for the nVidia seems to be faster than the Apple drivers.
In terms of number crunching, my 700 MHz G4 iMac is definitely slower than my Linux Athlon 2 GHz system. One calculation (3dDeconvolve) I just ran for comparison took 228 CPU sec on the Athlon and 417 sec on the iMac. Of course, you can get considerably faster G4 processors now.
I would recommend getting a lot of memory -- 1 GB or more -- no matter what system you buy. The datasets are large, and the auxiliary data generated during 3dDeconvolve, 3dvolreg, etc. runs are even larger.
If you like OS X, then I'd say get a Mac. I personally find some parts of OS X unpleasant and some pleasant. I'm just about to order 2 more iMacs for use in my group -- I think they make a good value replacement for a low-end Linux machine. I don't have any experience with high-end G4 Macs, so can't comment much on those.
bob cox
