There are some settings in windows to change the network layer. <A HREF="http://www.speedguide.net/Cable_modems/cable_registry.shtml" target="_new">This page</A> at speedguide.net has some registry patches/programs to speed up a network connection. Conversely, one could enter small values to cripple their network connection.
Note that changing these settings are "permanent" until they are changed back, and remember to record their previous values before changing anything! This is not a great solution, but it will definately give lousy throughput from your cable modem.
To make a poor network connection, you would want to change some of the settings to these:
DefaultRcvWindow ~ 200 (???? - try this one out - essentially it is the number of packets that can be in transmittion at one time, so will have the greatest impact)
TTL - no change
For most of the others, just pick the non-reccommended setting.
If this doesn't break you internet connection, it should drastically reduce it's performance.
I must re-iterate again, that changing these settings can seriously hurt your computer if you are not careful as to what you are doing. Don't blame me if it doesn't work
I have not yet begun to procrastinate.