If you want to see the screen, always good when you're configuring
then you'll need a video card. Nothing fancy, an onboard one will do.
You don't need sound, unless you want to hear it.
RAM depends on how many hits you are going to take, but starting with 128Mb is a good place to begin.
HDD space all depends on how big the website is. 80Gb is more than enough for linux to operate, the rest is storage space for web pages.
HTH