My father has a Mac laptop and he is running a Windows XP inside the Mac OS. It's like he is running another program when he opens Windows XP. Can this be possible with Windows 7 as well? He likes to install Windows 7 to his Mac book but I'm not sure if this will be alright.

If the macbook has sufficient resources then yes it it. It will be installed as a virtual machine just the same as XP is. Though why you would do that, I'm not sure.

I ask him the same thing and his answer was about security issues. He said that Mac is more secure than Windows so he wants Windows inside the security of Mac. It does makes sense to me until now where hackers are also targeting Mac programs.

The problem is that running Windows then makes the Mac OS vulnerable. It opens up the security issues that the Mac avoids-the Mac doesn't wrap it in a security blanket. Not to mention that it significantly kills the performance too.

I would think it would make more sense for him to maybe use a few of the different applications, such as MS Office or something like that, if he prefers the applications. It totally kills your security though to use Windows with the Mac.