For windows with limited file permission (Windows XP)
1. Install Apache in your folder profile "C:\Documents and Settings\your_profile"
2. Add the following directives to you httpd.conf
PHPINIDir "C:\Documents and Settings\your_profile\php"
LoadModule php5_module "C:\Documents and Settings\your_profile\php\php5apache2_2.dll"
AddType application/x-httpd-php .php
3. Edit the following directive to you php.ini
extension_dir = "C:\Documents and Settings\your_profile\php\ext"
4. Move the file libmysql.dll from C:\Documents and Settings\your_profile\php\ to C:\Documents and Settings\your_profile\php\ext\
5. Restart httpd using command line