I had no problem running logic on my older Mac Mini (1.6 ghz core duo, 1.5gb ram, 60 gb hard drive). This is quite a testament to how well written Logic is in regards to audio buffering and waveform redraws. Now that I am upgraded to a 500gb 7200rpm drive and a core 2 duo chip it is much faster. Sadly it maxes out at 2gbram (older intel model). It also does just fine on Photoshop and Illustrator. Though coming over from a quad core PC those apps may seem a little less snappy on a 2.66ghz mac mini. Though to be honest I think it wasnt until CS5 that they had quad core support?
My old PC is for playing GTA San Andreas now.