[charrua]

I dont seem to be allowed to attach the log here, but here is a quick cut and paste.

You can use http://pastebin.com/ to paste a full log, and then link it here.

I see others have issues with fanart and thumbs. My second machine automatically gets all fanart from the server but no thumbs.

Try this:

Another option suggested by MrDVD in a different thread is to replace the local thumbnails folder of each XBMC client by a hard link to a shared folder in the server. That way you won't even have to rsync all the folders. The only cons that I find in his solution are:
1- A lack on speed accesing the networked image cache (anyway be aware that two people reported that the lack of speed is none in their tests while I observed a noticeable slowdown in XBMC screen openings)
2- If you loose connection to the networked shared folder XBMC won't show any posters or fanart.
See this thread for more details.

Any suggestions? Will deleting all the tbn files in the movie folders on the windows box maybe make it quicker?

As pointed out by jmarshall, the image caching processes in XBMC take place in asynchronous separated threads, so they don't affect GUI speed. Also, the caching is only done once (the first time you access a media file) so if that was your problem, you wouldn't have it every time you use XBMC.

For what I see in the portion of the log you've pasted, I don't think the MySQL access time is the problem either, because in my case the time to retrieve movies from dataset is 1669 (against your 990), and in my case the GUI speed is ok. Try to paste a bigger portion of your log, and we'll see if there's anything else that can cause the GUI sluggishness you've described.