Stop Searching... This is the ANSWER:
I have been looking for the same app for my Samsung Galaxy Phone and my Thrive. At first I had been using Flickr Pro, and uploading my images to Flickr. Viewing them with the Just Pictures App works very well, as does the slideshow. but uploading is very time consuming.
I had tried many different apps to get a slideshow to work on my network, maybe 10 hours wasted. But I found Success.
I did have to root my Toshiba Thrive, after much research. Once rooted, I installed CIFS Manager which let me Map my Windows Network Share on Android.
Mapping the network drive on Android tricks the operating system into thinking the files are local, and thus lets you choose which application to open the files with. (you must be rooted)
After Mapping the drive you need a good File Explorer, I found ES File Explorer to be great but it has its own Image Viewer that I could not seem to turn off. So I am using AndExplorer and when I open an image... it asks which app to use!
And Quickpic is the best... I've tried many. Again Quickpic is the best! However if Quickpic had a better folder browsing layout and got rid of albums, a file explorer would not be needed.
Message to Quickpic DEVS: listen to our requests we will pay!