I've noticed the same problem as well, and the only thing that I can come up with is that ActiveState's repository is a much smaller subset of what's available on CPAN. Your best bet is to grab nmake from Microsoft, and use it to install modules that you download directly from CPAN. I haven't had any problems yet, but you'll need to remember that documentation does not get updated automatically this way as it does using PPM. Therefore, you'll most likey have to use pod2html and link it in to the ActiveState online html docs somehow.
Hope this helps!

Guildenstern
Negaterd character class uber alles!