Upgrading Windows on a Linux laptop

[Timothy Murphy]

I rarely use Windows on my dual-boot Fedora-20/KDE laptop,
but I'd like to update Windows XP to Windows 7 now.

I found when I did this on a CentOS machine
I was unable to get back to Linux,
and had to re-install CentOS.
I don't understand why, as I had saved and re-installed the MBR.

Am I wrong in thinking that this should be sufficient?
If not, what else do I need to save?

I don't intend to make any partition changes.

All suggestions and advice gratefully received.