Thanks a lot all, those are the best shots I've been able to get with that lens so far, but I'm not through trying. I'm thinking about posting a few more of this series to my gallery here if anyone would like to see more, let me know.
hcarvalhoalves - boy what a nick, I hope I spelled it right...The upper side of the wings is a gorgeous burnt orange, I have a shot somewhere, I'll try to find it. The bottom side you're seeing is multicolor with orange background and white blobs that have black rings around them. One of the best looking underwings in the butterfly world, most are much more drab and plain looking.
There are white butterflies though, the Cabbage Butterfly and Checkered White are both white with dark grey spots, and I think one of the Blues is a very pale blue, almost white, also very small.
Here's an older shot of the upper wings of a Gulf Fritillary, this butterfly, taken in Texas this July.
And a Checkered White, since you've never seen one. Taken in Oklahoma in June.