This is a decent link:
http://php.weblogs.com/php_vs_asp
I admit that I haven't actually read it (I never give ASP any thought),
but I saw that there are some links to other comparisons at the bottom.
Hope that helps.
Chris
=====
Chris Shiflett - http://shiflett.org/
PHP Security Handbook
Coming mid-2004
HTTP Developer's Handbook
http://httphandbook.org/