Oh, OK, that was the issue - perhaps this should be explicitly mentioned on the nsPerl wiki pages.
On my Win2K-sys I have Perl installed - that was why I didn't get errors.
I can't use the included functions because I need a complete set of regular expressions.
Perl offers me this - and if it's only the 800kb extra space I choose this as the simplest way.
Thank you for making things clear, now my installer works fine so far