I know heidi eraser cannot clean the free portion of a cluster if it is in use (cluster tips).
But what if I put my HD as secondary on an other pc and clean it with eraser?
Could it work?
Could I have some problem?
As the different OS is still Windows (especially Vista or Windows 7), it will still respect any file properties it finds on the non-system drive. That is why, for instance, if you have (or ever have had) System Restore enabled for a non-system drive, there will usually be a System Volume Information folder which the OS protects. But at least you are unlikely to get 'file in use' issues.