Bandwidth Sharing

Is there a way to setup my LAN so that two or possibly more PCs can access the internet at the same time without significantly affecting the other's experience?

I want to network my home but I'm thinking that since my brother loves to download stuffs thru torrent. When I tried the only PC connected to the net to download and surf at the same time, surf speeds suffer. So I was thinking that when I connect the other PC via LAN, the same thing will happen when one downloads and the other PC tries to surf.

I'm open to any suggestions (including limiting the other PC's bandwidth, though I'm not sure if this is doable), I'm planning to go wireless (which is why this thread is here), but if wired is the only way to go then so be it. I have not yet bought the router so if only a few of them supports what I wanted then please post them here too.

Thanks.