$ cat Config.pm
package Config; $VERSION=666666; 1;

$ perl -MConfig -le " print $INC{q!Config.pm!}"
C:/perl/5.12.2/lib/MSWin32-x86-multi-thread/Config.pm

$ perl -le "print for @INC"
C:/perl/site/5.12.2/lib/MSWin32-x86-multi-thread
C:/perl/site/5.12.2/lib
C:/perl/5.12.2/lib/MSWin32-x86-multi-thread
C:/perl/5.12.2/lib
.

$ perl -I. -MConfig -le " print $INC{q!Config.pm!}"
Config.pm

$ perl -I. -le "print for @INC"
.
C:/perl/site/5.12.2/lib/MSWin32-x86-multi-thread
C:/perl/site/5.12.2/lib
C:/perl/5.12.2/lib/MSWin32-x86-multi-thread
C:/perl/5.12.2/lib
.