• A fast PC ,but preferably a PC with a screen capable of a high resolution (1900 x 1200 preferably)
• A fast internet connection that is always on
• Some reliable hosting
• A domain name and an email address of your own
• You'll need software too, but much of what you need to develop your own sites is either free, or very cheap. The only really expensive software I use at the moment is Photoshop, but there are cheap (and free) alternatives to that too.