Speed Limit (Data Transfer)

Hello, let me explain myself...
i have placed this post in this forum since i am not being language specific, and also am not looking for a code solution, im just wandering if people could share ideas on how to make this feasible.

Basically i am trying to implement a way of setting up a speed limit on a file transfer, The transfer of the file is performed using the MS Winsock Control when i write in vb and system.net in c#

i would like to make it so users can select a upload and download cap for the applications data transfering

any ideas ??
thanks
Sam Lad