Limit Internet bandwidth usage on PC?

Hello, I have a problem with bandwidth usage on home’s laptop that my brother use. He often drains too much bandwidth resource from my DSL Internet connection line, causing many applications too be unstable or slow.
I was looking for an application that could “share” or limit the bandwidth between PC and Laptop to a more fair 50% or something.
I don’t have any particular skills in programming or anything, so Im looking for a simple program to perform this task.