Downloaded and installed my 64 bit ultimate Windows 7 today from technet plus no probs what so ever other than my usb wireless adapter wouldn't work but nicked one of the others from the kids upstairs and that one worked fine
This is what the release notes say MP3 files When MP3 files are added (either manually or automatically) to either the Windows Media Player or the Windows Media Center library, or if the file metadata is edited, several seconds of content may be permanently removed from the start of the file...