I just wanted to point out that your spider comes across as more of a spider-ant hybrid.
The fangs of the spider appear to be the mandibles of an ant. I believe this to largely be due to the shear size of the fangs. I suppose a large factor in this is also the fact that the chelicerae are obscured behind the fangs. Look here for an example:
http://encarta.msn.com/media_461517683_761566464_-1_1/spider_fangs.html.
Besides that I feel that you've taken the an odd approach to giving it six simple eyes. That is, you've given it eye cavities such as you would find on a lot of mammals. Not only that but it's eyes seem to be compound or apposition eyes. To make it look more like a spider you may consider studying their eyes:
http://images.google.com/images?hl=en&safe=off&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&um=1&sa=1&q=spider+eyes+close+up&btnG=Search+images. It seems that mostly their eyes bulge out directly from the rest of their 'head' and are separate entities.
Another thing I'm noticing is that you put ant legs on it. Ants have lumpy tarsi whereas spiders commonly have pointed tarsi as shown here:
http://insects.tamu.edu/ffa/senior/structure.htmlI suppose the idea behind my post is that you should spend a little time researching before you begin work on animals whose concepts are taken from the real world. At the very least a reference would serve well. If you want it to look like a spider, the advice is there, if not, there's nothing wrong with a giant spider-ant in a fantasy realm.