Installed Skype last week and coincidentally noticed my desktop PC's Apache installation was broken just when I wanted to test a malfunction Lightroom Flash web site. But by the time I connected the two events (I should have just switched off Skype's Port 80 access), it was too late and I had completely screwed up my Apache/PHP testing environment. After flapping around reinstalling incompatible versions, Core PHP was a perfect guide to getting PHP and Apache running on XP.