Found a post on this last night, didn't have this problem myself but this might help you.
For windows 7, go to control panel -> network and internet -> internet options -> connections -> LAN settings -> uncheck automatically detect settings.
Apparently worked for a lot of people with snail download speeds.
You, my friend.....just made my day!!!! :) :) :)
I was installing at ~1.5MB/s followed this and now i'm installing at ~4.5B/s