If you want to use PHP and Apache...I have heard that the newest version of Apache requires a "lot of love" when you want to use it with PHP...
I'm using the 1.3.27 Apache version and have 0 complaints!
Depending on how you plan to install you can simply go to Apache itself:
http://www.apache.org/
but I'm sure that's probably not what you wanted to hear...you wanted something more step by step...Then, try this one:
http://www.sitepoint.com/article/230
Depending on what you plan to do...you might definitley, absolutley, positively want to invite MySQL to your party; If you don't see why now, you will see why very soon after getting your PHP-Apache going...
So then try this one as well:
http://www.sitepoint.com/article/525/1
Good Luck!