PHP 4.2.3 and IIS4 and SQL7.0 and ASP

Hello ! I am first time installing PHP to my server and I must ask few things. Now server is this kind : WinNT4.0 SP6a IIS4.0 SQL7.0 There is several domains which use ODBC link to SQL7.0 from web-pages writed with asp. I wonder that if I install PHP4.2.3 version to same server what happens? Everything woks ? There is in PHP-4.2.3-Win32.zip install.txt and there is says : "In particular, with the ISAPI module, you are likely to encounter serious reliability problems especially on platforms older than W2K - you may witness a lot of server 500 errors and suffer from other server modules such as ASP also failing. You have been warned!" What means ASP failing ? Thanks to help!