i bought a mac mini about a year ago to go along with my iphone and to replace my noisy desktop pc. i am a huge fan of leopard osx and am amazed at how well the mac mini runs photoshop and any other hog of a program on such a small spec-ed machine. (1.8mHz 1Gig ram)
another huge turn on was that there are alot of opensource programs for mac osx. check this site for starters
Open Source Mac - Free Mac software, all open-source, all OS X.
i still rock the PC though. microsoft's not going anywhere, so dont shutout that CTRL key just yet.