If you are thinking about Linux, this is pretty much the worse approach possible. My advice would be to switch to open source applications first, to ensure that you will have a suite of software that meets your needs and that you will be able to transition your data. If the switch looks viable, spend some time using your chosen distro on live media, to ensure that it will work with your hardware. If the live media does not work, either try a different distro or set the transition aside. Then make the jump if, and only if, it looks like you will be able to make a total transition. Backing up your data and telling the distro's installer to use the entire drive vastly simplies everything from installation and support to everyday usage.

Linus itself is an excellent operating system that makes life for end users a lot easier, but I suggest the applications first approach since it is not for everyone. Even using this approach and testing it on live media first is bound to have a few hiccups, yet it is a lot better than starting out by learning everything from scratch or by troubleshooting major issues.