Jorge,
I haven't read all 11 pages of this thread, so i don't know if my response has been covered, but....
1. I love Macs. I detest PCs. So, i have a solid skew in favor of your 'switch.'
2. I bought a new G5-Intel MacPro in October, after having been using an upgraded G3 for about five years. I knew, going in, that the Intel machine would be running under Rosetta until all the software people updated their applications. I was happily surprised to find that Photoshop still ran faster on the new machine than it did on my G3 Dual500 upgraded to Dual 1.6ghz. On the other hand, when i rented a MacBook Pro in August, Photoshop ran more slowly than on my old machine. I don't know how the iMac compares.
The issue, though, is software. The hardware is plenty fast. But, you'd have to run the Photoshop CS3 beta to really see an improvement over CS2-rosetta. That's fine, as the CS3 beta is free until the official release (if you already are registered for CS2) - BUT:
The Plug-Ins i had been using with CS2 do not work with the CS3 Beta.
As of today, i believe that includes AlienSkin Exposure, and Digital Film Labs 55mm, two of my favorite filters. As well, i can't get a scanner import plug-in to use my Minolta 5400 scanner. I would have to buy VueScan or SilverFast or somesuch.....
Right now, i'm still going back to CS2 for scanning. Then shutting it down, launching CS3 for editing, if i have to do anything processor-intensive...Then shutting it down and launching CS2 again for 'polishing' and effects and whatnot. Not the smoothest workflow. I don't know if the Plug-In companies will release Intel-compatible updates, or if they'll charge for upgrades. Either way, they aren't available now, and i don't like the idea of having to pay for them.
But, that's that. The Mac is still a fantastic machine, and i have no doubts that you'll be a convert. PCs, by contrast, seem so primitive. The interface and OS are just so 'fugly.' As a person interested in visual arts, i don't understand how the aesthetics of the work environment can be ignored by PC devotees.
Good luck.