That's not a lot to go on - the cephalothorax is not clear, and with the legs all retracted, it's hard to figure out what sort of spider we've got, although from your diagnosis I'm guessing you think it's a crab spider. Maybe - although that's sort of an odd leg arrangement for a crab spider, I'm thinking. Anyway, first things first:

Where is this? Where was the spider found, what was it doing, etc. Then see if you can't get a few more photos, including at least one where it's walking around or at least has the legs extended. A lamp shining on it so we can see more detail would also be useful.

I don't think that's a crab spider: the front legs are not long enough. It looks like a orb weaver of some sort.

Could be somewhere in this neighborhood:

http://bugguide.net/node/view/73847/bgpa...

It would not be dangerous.

Also, what is your general location? It helps in the identification process.

Can anyone is this spider, I think it's possibly an ozyptila atomaria.

All I want to know is the actual name and wether or not it's poisonous.

Thanks.