I can confirm that the techniques from the link above work w/ a minor modification...
Steps to complete the iTunes 10.5 install:
1. Open Apple Software Update from your Start menu -> All programs
2. Click the check box next to iTunes 10.5 to select it only (deselect all other checkboxes at this time).
3. In the Tools menu of the Apple Software Update program select "Download Only"
4. After the download completes, re-open the Tools menu in the Apple Software Update program and select "Open Downloaded Updates Folder..."
5. The iTunes.msi file should be in that folder, move (not copy) it to a place you can access it from another windows computer (one of the shared folders on your WHS).
6. Follow the link in step two to download and install the MS software development kit so you can edit the .msi file.
7. Follow step 3 except instead of editing the "AppleMobileDeviceSupport.msi" file you are going to edit the iTunes.msi file
8. Follow step 3c to delete the line that checks for operating system and version.
9. Move the iTunes.msi file back to its original location (not sure this step is necessary, but hey, why not?).
10. Double-click the edited iTunes.msi file to run it and install iTunes 10.5.
11. When prompted to re-start, do so. When WHS reboots and you log in, iTunes 10.5 is installed and ready for use!
Here's the link again, just in case:
http://goolier.com/index.php/2010/09/itunes-10-on-windows-server-2003-or-home-se rver/
Good luck!