Well yes and no. I currently have 5 x 4.5" in the front and 5 x 5" PCD in the back. I have no idea why, but I guess the previous-previous owner had some good reason for it...
I already have a set of Cragars with PCD 4.5/4.75 and have another set of Cragars with 5 x 5/5.5" being shipped over as we speak. So I'll start with the current rotors until they're dead and then switch the rotors and wheels in the front to 5 x 5". And finally sell the Cragars with the smaller bolt pattern.
Bit of a hassle, but that's life.
If I'd live in the states, I'd probably sell the rotors and switch over to 5x5" straight away. But I don't. 