Hi,
Yes you can install PHP+MYSQL on Win98, what u need to do is that follow these steps
1)Download and Install mySQL for windows the interactive setup will automatically install mySQL on your PC.
2)Then Install PHP on your hard drive by copying PHP in your "c:\", then enter the PHP folder and go to the conf folder and open the "httpconf" file in any text editor and uncomment a line with your default port
127.0.0.1 and copy the following code in thehttpconf file at the end
ScriptAlias /php3/ "c:/<path-to-php-dir>/"
AddType application/x-httpd-php3 .php3
AddType application/x-httpd-php3 .phtml
Action application/x-httpd-php3 "/php3/php.exe
3)the start Apache web server and type local host in the address bar if you get a page which says "It has worked" then write a small php script eg. <?php phpinfo(); ?>
and if you get a page providing information about PHP then that is it.