Hi and welcome to the forums.
FYI the abbreviation for Macintosh computers is "Mac" not "MAC". All capitals denotes an acronym so there is no need to capitalise
I would look at getting a FireWire Cable so you can hook the 2 PC's up to transfer your Data, and apart from that take it one day to the next, and not knowing you, who you are and what you do, we have no idea in what
you need.
But once you get started i have posted a few links for you to browse at your perusal so enjoy;
Have a look at these for starters .....
Mac Switching 101
Mac 101
MacTricksAndTips ~ 100 Essential Mac Apps
Mac OS Menu Bar Items
Mac OS Keyboard Shortcuts
Mac downloads ~ Apple
Adium ~ Chat Client
Growl Notifications
SuperDuper or CarbonCopyCloner ~ Both make bootable copies of your HD
HandBrake ~ Video Converting
Burn ~ As it says A Burning App
Transmission ~ p2p client
Skitch ~ Screen capture and more
VLC ~ Video player that plays most codecs and does a lot more
Perian and Flip4Mac Makes watching certain codecs easier ... This is Essential IMHO
Audacity ~ Play with Music App
CandyBar ~ Mods all your icons, and dock
MainMenu or Oynx ~ Does the same as Disk utility only more thorough
Quicksilver ~ Works like Spotlight but way way better and does so much more
StuffitExpander ~ Opens Zip and rar files and more
Lil Snitch ~ Firewall type App that looks at your incoming and outgoing traffic
and last but certainly not least .....
AppTrap ~ Once installed it sits in System Preferences and deletes all associated files of anything that you put in the trash ...
Should keep you busy for a while lol
HTH
Cheers
EDIT : There are a lot of good Apps already on your Mac so look there first. These i posted are some of the common ones used by Mac users.
EDIT 2 : Also have a read of this Sticky written up by one of more knowledgable members chas_m ~
Sage Advice for the New Mac Switcher . . .
And most importantly have fun with your new Mac and dont worry about buggering something up in the beginning as a reinstall is only a couple of clicks away. I also suggest having a spare ext HD for Back-Up as you never know when something will go wrong, and if you need to re-install all you prized pictures and music and data is save
Cheers