The Mac version will run, and had version parity with the last version of Windoze NWN - BUT…
The Mac version was coded back in the day when Macs ran on Motorola. Your new Mac will be an Intel processor. In order to run the Mac version on Intel, it runs in emulation, and it steals acres of performance, and even if your new Mac has a fancy 256-512mb vram video chip, running it in emulation isn't smooth at all.
Easiest bet is to make a bootcamp partition, with Windows installed, and just reboot to Windows when you want to play.
Second bet which is a little effort on the top end, but avoids reboots, is to run it using Crossover. http://www.codeweavers.com/products/crossover/