I'm having trouble getting XAMPP and Perl to play nicely together.

In my opinion, you should drop the XAMPP altogether if you are doing significant stuff in Perl. The newer XAMPPs are PHP centered and Perl is just an appendix - to be installed afterwards. The XAMMP system throws a lot of stuff on your computer and there are several versions and version extensions around. Don't do that. Install Apache 2.2.8 on a system w/Activeperl 5.10 or so. XAMPP has it's own 'builtin' Perl, I don't know if you may use your Activeperl easily (I think it's not worth the effort) with XAMPP.

Apache 2.2.8 + Activeperl 5.10 + mod_perl 2.0.4 works nicely, without XAMMP. Even adding a PHP 5.2.5 into your system poses no problems. I did this a million times on several Win-XP boxes.

Update:
The OP did get it to work (at least as external Perl-CGI process), so my above rants may be considered as anti-XAMPP advocacy ;-) ... But I'd consider it difficult to load an external mod_perl (non XAMPP - mod_perl => installed into Activestate Perl) into the XAMPP-Apache process (but might work too).

Regards

mwa