I would just reinstall because you're gonna need new drivers to go with Windows and that gets tricky if you simply roll back the OS or do a system restore to a previous date.
However, if you have the option, you can use specialized software like True Image's Universal restore to make a backup copy of the OS as-is and then simply apply it to the new hardware after it's all been installed.
There are a couple of other pieces of software that will do the same thing if you'd like to save some time reinstalling everything.