Sounds like caching is still a problem for you.
Are you running any "Web Accellerators", like from Google, AOL, NetZero, etc? All of those do weird things with stats here on this site.
4Mbps down, and 384kbps up is normal Comcast (for the SourthEast that is). The higher service is Premium. If they had something faster, I'd be paying for it but they don't.