I tried this on one machine, works great! Then I went home, tried to show it to someone, and got this message:

Bad option `-disabledforeground' at c:/Perl/site/lib/Tk/Widget.pm line
+ 196.
 at kmeans_clustering.pl line 24
[download]

I'm sure it's a version thing, this is before:

ppm> query tk
Querying target 1 (ActivePerl 5.8.0.806)
  1. Tk [800.024] A Graphical User Interface Toolkit
[download]

In the process of upgrading, but thought you'd like to know...