I am using ActivePerl on Windows 7. I installed PAR and attempted to convert a simple Perl script to a .exe using pp.
Just wanted to point a few things so that others don't get confused. First, unless you're using an older version of PAR, you will need to install PAR::Packer in order to get the the pp utility. (From PAR::Packer, "Since version 0.97 of PAR, this module and its related tools such as pp have been stripped from the PAR distribution and are now distributed as the PAR-Packer distribution so that PAR users need not necessarily have a C compiler.")
Secondly, ActivePerl can't install PAR::Packer directly from CPAN without some additional steps. For 32-bit ActivePerl, you'll need to install MinGW and dmake from ActiveState's repository. For users of 64-bit ActivePerl, there's more challenges with the compiler situation, but I'm not familiar with all the details.
As for the problem that you're hitting, I agree with 7stud that it definitely looks like you're not using the correct syntax.