This has frustrated me and took awhile but here is the method I used. I tried using xml2m3u, but the m3u were not able to be read by media center. As a background, I had 5300 songs rated in itunes and not media center.
Steve- you may want to sticky this?
Here is my method of converting ratings from Itunes to Media Center
1) In itunes create a smart playlist for each rating (one star, two star, etc...)
2) On your desktop, create a folder for each rating (a folder named one starm two star, etc.)
3) In itunes open the playlist for one star
3)Highlight all songs (control A)
4) Drag the contents into the corresponding folder on the desktop (this will COPY all of the songs from the music directory to the new one)... Only transfer one smart playlist/rating at a time
5) In media center, import that folder.
6) In media center, create a smart playlist for tasks.. Audio- possible duplictaes
7) Edit the smart playlist to say [artist],[name],[duration] (add duraiton to the string)
Click on the smart playlist in MC to open it
You should see many duplicate entries
9) Click song name to sort by song name (if you had previous duplicates in your library, don't select them if you dont want to change the rating... by adding the duration string, you will decrease the chances of having duplicates that you dont want to find)
10) Highlight everything that is a duplicate that you want to change the rating
11) change the rating to whatever you want it to be
12) Now on the desktop delete the new folder you created (your music should still be in the original folder, this was a copy)
13) In media center, import another new folder and go again (and make sure the box is checked to remove broken links so the old folder is removed... if you dont the duplicate list wuill be tainted
This takes a long time. Most of the slowdown occurs copying the music from itunes to a new folder (it took 45 minutes for one fodler which had 2500 songs)
Also, make sure you have space on your hard drive to copy music to a new folder.