The Windows OS file system is case-preserving but case-insensitive.

c:\>cd @wOrK\PeRl
c:\@Work\Perl>
c:\@Work\Perl>dir uPD*
 Volume in drive C is Acer
 Volume Serial Number is 1234-5678

 Directory of c:\@Work\Perl

02/13/2010  07:57 PM             4,098 Updfxgen.pl
02/13/2010  07:57 PM             3,956 Updfxgen.pl1
02/13/2010  07:57 PM            33,199 updgen.pl
02/13/2010  07:57 PM             1,732 Updungen.pl
02/13/2010  07:57 PM             1,589 Updungen.pl1
               5 File(s)         44,574 bytes
               0 Dir(s)  256,281,104,384 bytes free
[download]

Update: Expanded the example. Also: Perl commands for the Windows API (not for the command line!) accept a / (forward slash) just as well as a \ (backslash), alleviating the need to escape backslashes in double-quoted strings.