Off-topic: 'bandwidth shaping' on DSL network

[trader <trader_wiz@xxxxxx>]

Managing three PCs all indipendent, no server (their IP Gateway is 
router's) that  access the internet using a Zyxel Router ADSL 642R,  I 
would like to 'force' one of the 3 PCs to use a much less bandwidth such
as 9600/14400bps instead of leaving the free access to the maximum 
bandwidth the DSL router can offer.

Is there any software (or tweak) to be installed on the specific PC able 
to restrict (bandwidth shaping) the net access  but leaving the usual 
bandwidth to the other two PCs?

Thanks,
Albert