Well if you know that people have their own opinions, then don't come to another forum trying to sway people towards buying a PC. If they want to get a Mac, let them get a Mac.
Apple doesn't "lock" people out. Security is good, and that's another reason why there isn't any spyware or viruses out on the Mac platform. Windows Vista is following the same scheme, whether you like it or not. It's much more annoying in Windows, because in fact, it's still Windows.
As for design apps, the "work environment" is different for each OS. The great thing about a Mac is that each program isn't in its own window. It's much easier to navigate through several windows on a Mac than it is on Windows. Your taskbar gets cluttered, while in OS X you can use Expose, etc. And alt + tab does get much more annoying when you have a lot of windows opened in Windows. Windows also has a few problems with font management, especially if you're using Flash. These are just a few quirks, but nonetheless, they're all just quirks. It's not "BS" that Macs are for designers, because there's a lot more hotkeys and not as many "quirks" to deal with. This helps with productivity. But aside from those facts, yes programs do work the same on both platforms. They're made to be that way for cross-platform compatibility, aside from the OS environment. Who cares if a program "hangs" for 30 secs. It's all about the work environment.
As for universal apps, some companies do it, some companies don't. It's according to their business model, and how much of a demand there is for the market type. And people don't have to buy two types of computers. Because now you can get one, an Apple computer.

And even that, if you don't need OS X, then you can get a PC. It's a computer.
What kind of car do you have?