If your old HDD is alive copy from c:\Mach3 folder the following:
Mach1lic.dat
<yourmachineprofile>.xml
whole folder:
C\Mach3\macros\<yourmachineprofile>
C:\Mach3\Brains

OR

whole C:\Mach3 folder and rewrite it on new machine (if Mach version is tha same)