Thanks for editing your profile.
Even though you probably used the XAMPP installer to install 1.7.7 it does not add content to the Windows registry unless you are running the components as a Windows service. ie you have ticked the Svc check boxes or ticked the Services in the newer XCPv3 Control Panel.
So if you stop all components - Apache, MySQL FileZilla etc. - and remove the ticks in the Svc check boxes so you have no component running and no component installed as a Windows service and you have exited (clicked the Exit button in the control panel or the Quit button in the newer control panel) then you should be able to copy the XAMPP folder to your new hard drive after reinstalling your OS if required.
Then you would simply run the setup_xampp.bat file found in the xampp folder to set the new path location in all the XAMPP system files.
You would need to edit any paths you have in your own files and folders to reflect the changed location if it different to the current location.
If you are not changing location of XAMPP but simply installing a new drive for your OS then you should still following the above instructions to make sure you have uninstalled all Windows services and made sure that all components including the Control Panel are stopped and closed - there should then be no need to run the setup_xampp.bat file as your path location will not have changed.
I never use the installer version of XAMPP, I use the zip installation method but that should not make any difference and to prove the above instruction will work, I have just installed Win7 on a new computer and copied all my XAMPP versions to a new SATA drive that does not have Win7 on it.
Then I ran the setup_xampp.bat file in each version (I have most versions installed for troubleshooting in here) because the drive letter was different and all versions are working perfectly with absolutely no lost data, files or folders.
In brief - make sure all components are stopped, all Windows services are uninstalled and the CP is exited before installing the new OS and drive.