so I run a triple booting hackintosh to the same specs as a $6000 power mac pro or whatever the fuck the call it. even shelled out for a legit copy of OSX and it only cost me $2500 all up. Does everything Apple's hardware does. I use it to dev iPhone/iPad apps and boot to Windows 7 x64 for design and stuffs. I've got BSD set up as well for testing firmware etc from embedded projects, but I hardly ever boot into that, so for all intents and purposes it's a dual boot system.
The OSX UI is leagues better than windows 7, and the install process is better than Win7 too, however of late a lot of programs seem to leave behind junk on uninstall. It's pretty easy to clean up though, just like it is in Win7, if you know what you're doing. If OSX had all the programs Win7 supported, then I'd switch in a heartbeat. Not a fan of having to run some apps in Parallels or some shit.