What kind of spider is this?

[Pepper]

On Monday I happened upon this amazing spider and it's web. I've not had any luck identifying the spider, and hoped that someone here might know what it is. Anybody ever seen one? The back of the spider was very yellow on the edges and black in the center. I was unable to position myself for a clear photo of the back. Here's a photo of the underside as it sat waiting for a strike on the web.

Also, while it appears in some respects to be a "Saint Andrew's Spider" the markings on this spider are vertical, and all the photos I found of a St. A's are showing horizontal markings.

Additionally, I did locate a photo of a black and yellow garden spider, which looks quite different markings-wise, but shows the interesting "reinforcement" woven into the web, just like the one I saw. Click here for the link to that spider: http://www.enature.com/fieldguides/d...?recnum=IS0107

So, I'm looking for some expert guidance. Anyone?

Spidergirl?????????????

Thanks,
Pepper