Make sure you have checked your connection in;
Tools > Internet Properties > Connection tab.
Ensure never dial is selected and then go to LAN Settings and UNcheck everything. Also try plug ur dads internet cable into ur computer to eliminate cable/router problem. Also seeing u just reinstalled windows is ur computer going ten to the dozen downloading windows, nortons etc updates thus limiting ur download speed for everything else. If that doesnt work try another internet browser like google chrome, firefox or reinstall/upgrade explorer. Otherwise reinstall ur broadband software.
Im no expect so im out of ideas now.