If you got your hands on a copy of the PowerPC version of NT4, maybe, but nothing recent.
You can install Windows inside of a virtual machine such as VirtualPC or VMWare, but on an iBook G4, it's going to be slow to the point of being almost unusable.
Personally, I'd encourage her to stick with it. There really isn't that much in the way of fundamental differences in the way Windows and Mac OS X operate. The only major differences are using the Dock and Expose instead of the task bar, every program sharing the same menu bar, and having to actually tell a program to close instead of just closing the last open window. Most of that just takes a little time to get used to before it becomes second nature.
Maybe you could get her a book on using Mac OS X. I consistently hear good things about the O'Reilly Missing Manual series as being very good for beginners and even experts alike. Be a whole lot cheaper than getting a new laptop. I'd also suggest encouraging your daughter to become more flexible about things in life. Learning to flow with change, so she doesn't get so stressed about trivial things like minor differences in computer operating systems. She can save all that angst for things that deserve it, like mortgages, car loan payments, marriage, etc.
Is it at all possible to format and install windows on an apple laptop. I bought the laptop for my daughter who I believed would be able to navigate Mac OS but she is so familiar with windows is struggling with her laptop. Any assistance would be a great help. Even if the answer is no.