Spider!

We found this spider spinning a huge web outside our front window and I have no idea what it is. The girls and I have been watching it for a few days now. The huge rainstorm we had demolished its web, but it rebuilt it. I threw a shrub branch into the web to show the girls that it'll attack whatever lands in the web (I actually tore part of the web down doing this), but it amazingly got rid of the branch and rebuilt again. I want it gone, but Jeremy says to let it be. I took a couple pictures and tried to identify it online and am now totally creeped out by all the spider photos I just looked at. I think I'll put it in a jar for the girls so observe it up close and then set it free - far away from our front door.

Here's looking at its underside. Gross.

And again...
And here's one I found online that I thought matched - it was unidentified, but it has the same orange "armpits", black and yellow striped legs and the two white dots on its back end. So gross!