I've got MU partially integrated. The only difference between it and WUv6 is that it also includes a file muweb.dll, which must also (along with wups2.dll) be registered. However, Tools...Windows Update still defaults to WUv6. Also, the first visit to MU still requires the user to go through the "Start using Microsoft Update" stuff (though nothing has to actually be downloaded from the site). After going through that, Tools...Windows Update points to MU like it's supposed to. I think MU is going to eventually replace WUv6 once the kinks are worked out anyway, so this may be a moot point. Given the current bugginess of MU, I'm actually OK with it defaulting to WUv6.