Never Mind, i found my answer, it turns out the msvcrt70.dll can be renamed. After renaming it, i can freely copy the new file so it will be used the next time VFP Starts. Here's my code

Declare Integer CopyFile In Win32Api String, String, Integer
Declare Integer MoveFile In Win32Api String, String

=MoveFile( lcFile, lcFile + ".OLD" )
=CopyFile( lcNewFile, lcFile, 0 )

>I have a VFP 7 exe installing an upgrade to VFP8, i install and register everything fine, but when it comes to msvcr70.dll i can't replace the file because it is in use by my VFP 7 update program. The msvcr70.dll is in the \winnt\system32 directory.
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>How can i replace this file in a VFP Exe ?
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>Thanks.