iTunes 10.5.3 for Windows XP, Vista or Windows 7
http://appldnld.apple.com/iTunes10/041-3782.20120119.Ase34/iTunesSetup.exe
iTunes 10.5.3 for Windows (64-bit)
http://appldnld.apple.com/iTunes10/041-3784.20120119.Qap3E/iTunes64Setup.exe
iTunes 10.5.3 for Mac OS X
http://appldnld.apple.com/iTunes10/041-3779.20120119.Bgty5/iTunes10.5.3.dmg