I'm new to XBMC and with the setup I have I'm not sure where to turn to except the experts at AVSforums!

I have a generation 1 AppleTV with XBMC installed. I also have a HTPC in another room with 3TB of storage, ripped Blu-rays and video files. I would like to play those on the AppleTV using XBMC but I'm having trouble sharing.
It's the age old AppleOS no liking Windows. So I'm wondering if anyone has this setup and if so what they did.
I have the folders shared on my windows machine and XBMC on the ATV can find the computer but when it asks for the username/password it doesn't advance past that stage. I've inputted the correct combo and can't figure it out. I've even tried the IP address of the computer...no dice.
Any help would be appreciated. The root question is an Apple install of XBMC not being able to view videos from a Windows 7 PC.