I have seen (on Comcast) through the same modem and router, a questionable desktop with XP get 8 down and 4 up constantly while the new laptop with win 7 was getting 113 down and 5 up constantly.
usually that is a difference between NICs, system specs as well as processes.
its probably something simple like they've oversold DSL in the area, he's over 100yds from the switch and old lines in his area.