Mac is walking away with the awards, and for good reason. You get the best bang for your buck.
First off, Apples have the lowest out of the box failure rate. They have awesome support. They are not plagued with viruses etc. Mac has a built in firewall.
You can run windows and windows applications if you feel you have to, it comes with a nice set of software.
Did I say they have awesome support. I have spent years on pc's. Most people ask me for help with their windows machines. I own a Mac, if I have a problem, I jump in the car, take the time to drive to an Apple store and it gets fixed. Yet sitting on my dining room table, I now have not 1, but 2 HP's, one with a broken CD drive, another that is so infected with spyware and adware that it takes 15 minutes to shut down, and longer to power up. Neither one of these people created a recovery CD. The one with the good CD drive has a corrupt partition so the recovery D can't be created.
You may wonder why I am adding this, it is because most people are not technologically savy enough to know how to maintain and rebuild a machine.
The people at the genius bar at the Apple store are there to do this for you.
Go Apple.