PHP's switch/case statement is like a big if/elseif/else statement. I use it all the time. I think the PHP documentation explains it well--not sure I can make it more clear.
http://www.php.net/manual/en/control-structures.switch.php
You don't have to use switch/case--you can use if/elseif/else instead, but switch/case is cleaner. Also, switch/case allows you to setup conditions where more than one test is true so multiple case sections fire--although I've never done this in my thousands of lines of PHP code.