I am using a modified hosts file:
http://www.mvps.org/winhelp2002/hosts.htm
That along with HostsMan app, they list a hand full of MS servers in there, I remove them but every now and again I still get the "Loading..." caption in the ad box, there is probably an obscure server in there Microsoft now uses.
Hence I need a list of all the ad servers/hosts that Microsoft uses, no reason this isn't publicly available somewhere anyway, but I can't find them, no doubt someone here knows.
Edit: They must use more than *.msn.com