Running Microsofts Internet Information Services (IIS) and a SQL Server on the same development box as WAMP can sometimes cause port conflicts resulting in Apache not starting. Suppose – hypothetically speaking – you’ve recently decided to spend some time setting up IIS server and an MS SQL server on a Vista box (Windows Vista Home Premium in my case).  Then later you switch gears and after setting up IIS and MS SQL server you decide to do some Apache and PHP development only to find that Apache is blocked on port 80.