me too.. i canceled the update via WU. I think it's a bug cause the download is at its full speed and the progress bar moved after downloading 250 MB !, maybe the WU is downloading the ESD file multiple time in the background because of a bug or something.
Even if they don't allow us to apply color to titlebar, aero glass by bigmuscle will fix this... there is also another method I'm currently using to change the color of window borders, but let's hope it will still work in the final version...
Stop WU service => delete everything in Windows\SoftwareDistribution\Download => Start WU service => Check for updates