If I use the following line on a UNIX server (running PHP 3.0.9), the test works as intended...meaning if "</body" is the first entry on the line, the test returns true.  I am 99.9% sure I have the exact same line on my test machine running PWS 4.0 (I can't check from here).

if (strpos(strtolower($line), '</body') == "0") {

However, on IIS 4.0, if $line is a value that does not start with "</body", the test still returns true...I'm assuming this is because strpos() returns "" (false, which it does) and the parser compares that to "0" and assumes "0" is false, therefore the test "if (false=false)" returns a true value.  I can get around this by changing the test to

if (strpos(strtolower('a'.$line), '</body') > 1) {

...but it seems to me that the function/parser should work the same under PWS and IIS and UNIX.  I was just confused why my page worked on the UNIX server and wouldn't work under IIS.  BTW, I have tried both the CGI and ISAPI versions, and both behave the same way.