Hi there, first of all, congrats on your Mac.
Avid Mac user myself, so maybe I should share how I use my Mac (playing poker that is).
Set-up / Gear:
MacBook Pro 13 inch 2.4Ghz Core 2 Duo with 4GB RAM
Connected to a Samsung 24 inch SyncMaster BX2431 LED monitor
Aluminum Apple Keyboard (not wireless) with numerical pad
Razer Mamba (wireless mouse, but playing wired)
(cheap) Hercules soundsystem/boxes
Applications
*I play on PokerStars and Full Tilt (stopped for a while, trying Pokerstars again), so those sites support downloadable Mac clients.
I'm also testing out Lock poker, Carbon Poker, Winamax, BWIN, Absolute poker and Betfair. So these pokersites have desktop apps for Mac as well.
*As my tracker/hud, I use PokerCopilot 2.
I tried PT3 for Mac, but it was 'heavy' and 'clunky'. Though it has more funtionality than PCP2, I prefer simplicity and cleanliness of it + more mac-style with PCP2. Limited in stats comapred to HEM and PT3, but (for now) PCP2 just provides everything I need, because I'm just a 'beginning' player.
*I use BetterSnapTool to resize/organise my tables and windows/programs into equal tiled sizes.
*BlazingStars is like Autohotkey for windows. So, using keyboard instead of mouse + visual and software aid
(! Not using this at the moment, because I'm building my pokerplaying from the ground up again. I used to multi-table, therefore I had to use BlazingStars to make it easier. But now, I play 4 tables, 'cause ... I just want to improve :-) )
* Crossover & WINE (Winebottler): are apps that make .exe files (windows based programmes) run on your Mac. Crossover is not free. Wine/Winebottler is.
I use these apps so I can run : PokerStove (The Mac alternative is PokerZebra, but Pokerstove 'can' do more)
and Fergulator (Google Chris Ferguson Bankroll Management), an program where you can type in your Bankroll and calculates BRM.
* Skype , Mikogo, Teamviewer, Adium (all-in-one messenger), Tweetdeck, NetNewsWire (reading blogs)
These apps I use for social networking
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Bootcamp or Parallels or VMware?
Mac has Bootcamp installed. It starts your iMac into Windows. Once started in Windows, you need to restart in order to run Mac OSX.
I also have VMware, but not using it anymore. Why? Because I realised: Why run windows programs in an 'unstable' environment? + If I can play poker fully on Mac, why should I bring down my Apple/Mac experience by running Windows on it at the same time? Power/resource- loss!
I hope I answered most of your questions with this post. It's getting pretty long now, so if you have any questions, just ask
P.S. These are just how I use my Mac playing poker. I'm a lawstudent, so I use other apps and stuff as well to handle that part of my life.

If you need more info on that aspect of my Mac-use, just PM me or something. I'll be glad to help you out!
Greets
J.