I run UTAU version 4.18 and MMM version 1.2.3.6 on Windows 8 64 bit. They work fine, (MMM still needed some old add-ons). Also If you use UTAU and you put in your Program folder(s), make sure you give yourself (either your account or the all the accounts on your computer, if there's more than one account) permission to read, edit and write folders or you won't be able to save and edit things like your oto.ini of your voicebanks.