I've had issues installing Tk on Strawberry too, but always get it to work. Currently Windows 7 x64 w/ Strawberry 5.18 64-bit:

VinsWorldcom@C:\Users\VinsWorldcom> ver

Microsoft Windows [Version 6.1.7601]

VinsWorldcom@C:\Users\VinsWorldcom> perl -v

This is perl 5, version 18, subversion 1 (v5.18.1) built for MSWin32-x
+64-multi-thread
[...]

VinsWorldcom@C:\Users\VinsWorldcom> perl -MTk -e "print $Tk::VERSION"
804.031
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IIRC, it was a 64-bit thing. Anyway, here's the fix I use:

http://perlmonks.org/?node_id=899504
http://www.nntp.perl.org/group/perl.win32.vanilla/2010/07/msg252.html

Go to the downloaded working CPAN directory of Tk

  cd pTk\mTk\xlib\X11
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Edit the file 'X.h'.

Starting at line 43:

43: #ifdef _DWIN64
44: typedef __int64 XID;
45: #else
46: typedef unsigned long XID;
47: #endif
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Change to:

43: #ifdef _DWIN64
44: #include <inttypes.h>
45: typedef __int64 XID;
46: #else
47: typedef unsigned long XID;
48: #endif
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Go back to root of the build directory and:

  dmake
  dmake test
  dmake install
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