OS X :: File Sharing From Mac To PC?

For the life of me, I cannot share movies stored on my iMac with any other device except my Apple TV.

I currently have most of my movie library archived in iTunes (90+ movies) that I converted to .mp4 or .mv4 using Handbrake. All of the movies are available on my AppleTV. I have three networked PCs, one ethernet, two wireless. I have enabled file sharing to all computers. I have installed iTunes on the wired PC as well as one wireless PC. I can share my iTunes music (but no video) between the iMac and PCs.

All three PCs are Windows XP SP2 machines. I can navigate to the movie folder located on the Mac on any computer. I cannot open any movie file. I can open and access shared PDFs, spreadsheets, word documents, pretty much anything I have access to EXCEPT the movies.

I CAN copy the movie from the host Mac to any PC with no issues. Then, Quicktime will play the movie. But, no matter what I try, I cannot stream the movies to any other device, except the Apple TV. (There are no movies stored on the Apple TV. I have a Time Capsule managing a wireless network that streams movies with only a few seconds delay.) I could see there being a time lag streaming a movie to a laptop with 500mb RAM and a G wireless connection, but the wired PC is connected with ethernet. It WILL allow me to copy a 2Gb movie from the iMAC to the PC in less than three minutes.

I initially only had "Read" permissions on the folder in question, but I did try "Read and Write" access to see what happened. Nada.

I cannot find a definitive answer as to sharing movies with iTunes. But, even if iTunes will only share music libraries, I still think that I should be able to stream movies by accessing the file directly. The wired PC is in my daughter's room, and I would like her to be able to stream movies from the iMac. If I navigate directly to the folder in question, one of two things happen. If I try to open a .mp4, I get "Error 50: An unknown error occured" If I try a .mv4, iTunes will open, but nothing happens. I can view the movies playlist under my shared library, but nothing happens when I attempt to open one.

Eventually, I would like to softmod a used XBOX my sister gave me to stream movies on the iMac to another TV. I even tried XBMC on the wired PC to act as a media manager since iTunes would not pull movies off the network. It will find the movies, but it will stall (I did not let it keep trying after 15 minutes of "buffering" a movie.)

I know I'm not the only one trying to share a library. Even if iTunes will not let me do it, I should be able to set something up so others on my LAN can access these files.

iMac specs:
2.4 GHz Intel, 2G RAM
OS X 10.5.5

Wired PC specs:
1.99 GHz Intel, 384mB RAM
XP SP2
XP SP2