r2b2: Just to throw something into the mix, my connection is ex-TCL cable and I'm on 203.97.X.X but I haven't come across any particular issues personally.
(Although now I've probably just jinxed it!)
Have you tried any of the sites that have been listed on this site as problematic such as www.hgst.com or us.battle.net/wow/en/ ?
Would be could if you could try them and let us know how they go :)
Brumfondl