<p>I am using ActiveState Perl 5.6 on a Windows 2003 Server, and am having some memory leak issues.  Are there any good tools (or even bad tools which would give a clue) which I would be able to use to help find them.</p>

All perl program memory leaks will either be an XS holding onto a reference, or a circular data structure.
Devel::Cycle
is a great tool for finding circular references, if you know what structures are likely to contain the loops.
Devel::Peek
can be used to find objects with a higher-than-expected reference count.
If you don't know where else to look,
Devel::LeakTrace::Fast
could be a good first place, but you'll need a perl built for debugging.
If you suspect the leak is inside XS-space, it's much harder, and
Valgrind
will probably be your best bet.
Test::Valgrind
may help you lower the amount of code you need to search, but this won't work on Windows, so you'd have to port (at least the leaky portion) to Linux in order to do this.