You have the MSBlast worm my friend. Get rid of it (either read about it <a href="http://www.tfproject.org/tfp/showthread.php?s=&threadid=22022">here</a> or run windows update if you can).
Once that is taken care of, see if the issue is still there. If so, post
Also, if you have a spare 486 or low end pentium, you could use it as a linux router. IMO, Windows ICS makes your connection rather slow.
//edit: Also, forgot to mention, that if you choose to go the linux router route, you will be protected a bit better as it serves as a firewall. And you would need a hub/switch.