For ease of use it has got to be a Mac - generally much more intuitive than a PC. Rumour has it that Macs do not crash as much although that is not my experience - i find them about the same for performance and stability (PC with Win XP).
You can run programmes made for PC's on a Mac using an Emulator programme which cons the software into thinking its on a PC - I've heard good and bad about these.
As far as I'm aware (not being a hard gamer) there are not as many games produced for Macs and it doesn't seem to be the machine of choice for those that are into games.
Generally Macs are just as convenient as PC's and the amount of software available will be sufficient for most users.
For pure design the latest Cube Macs are the business.