Full Tilt has a mac client. I use it, its good.
PokerStars has a mac client too. I guess I missed this when I was doing my own transfer to mac.
NLOP needs dotnet framework v2.0, so you'll actually need Windows for that to run. They do say there's a mac client coming soon...
To run windows on your mac, you need an Intel mac. Most macs made in the past few years are Intel and it sounds like yours is brand new so I'm sure you're good to go.
To run windows on your mac, you need
VMware fusion or
Parallels, and a copy of windows itself. Alternatively, you can try for free
VirtualBox. I've never tried it, by the time I heard of it, I already had Parallels. There's a tutorial on how to install and use it
here.
You can usually use the windows CD and activation keys that came with your old or existing computer on your virtual windows installation.
Good luck, happy gaming, and welcome to the mac community.