Ello,

Not a simulator, you can run Mac-OS-X natively on most Intel machines. Apple stopped making their macs with Power PC chips, and are now purely Intel based, just like your desktop PC.

If you got OS-X 10.5 (aka Leopard) and patch it, you could install it and run it on your PC natively (though it can take some time to get the drivers right). Like Vista, you can buy Mac OS-X Leopard without a computer. This works best with a dual core intel chip with SSE2 and SSE3. I have heard that you can do it with a Pentium IV and SSE2 only though. No idea what SSE actually is, btw

Mac OS-X will identify your computer as a Mac Pro. So you are not simulating Mac OS-x, you are actually running it, and as far as the operating system is concerned, you are using a real Macintosh. But not as a window within Windows, but as a separate installation. Lots of people are doing this suddenly, now that the newest version of Leopard is much easier to install on non-apple PC's.

Also, it is possible to just install it to an external USB hard drive and boot from there. And then boot normally when you want windows.

Some drivers for sound cards and wifi don't work out of the box, though, and some people have resorted to sticking little USB wifi and sound card dongles on their PC's, which do work. (and you can get for less than 25 EUR apiece)

People are discussing this alot at insanelymac.com. It's a very hot topic all of a sudden. I for one can vouch how much nicer OS-X is than vista.. is smooth and creamy.