Okay, Deadguy...
I too have a P4 2.8GHz, but I have 512MB of RAM and an onboard Graphics Unit. On SP I managed to get 60 frames max on 3.7... but Multi is a different story. It started out at 30, slowly got to 24, then crunched to 5. Browsing the internet slows it down to lowest 10. Multi I average 18-25 now. and I have a crappy GPU compared to you.
Internet settings, disable 255.255.255.0 connections. In windows, use the Security TAB to remove access to the Windows/Temp folder. Those helped the most with my ToriFrames. And try to move away from Windows Based software, and if you can, cut off internet communication to all but the DNS and DHCP services.
Didn't see dial up, lol. And if the connection is free, the average 1.3k per second shouldn't affect you, lest of course your downloading