Limit roommate's bandwidth without him knowing?

Hi, we have a huge problem. I live with 3 people since rents are expensive and stuff. Anyway, we pay $60/month for 512k/256k cable, I realize it's a tad expensive for the speed but that's the only provider we have available here in my area. We have 3 computers hooked up to a Switch, which is hooked up to the cable modem.

Ok the problem is this. One of the housemates (let's call him housemate2) sits around all day downloading stuff. He downloads 24/7. That is ok during some certain periods of time, but then at peak hours it affects my gaming and housemate3's gaming as well. I realize connection at peak hours are generally slow, but i know for a fact that turning off his downloads help on our connections.

To try to solve this problem we've talked to him and assigned download hours, which in about a month he forgets about them.
We also have downloaded Netlimiter, and i had to remove it since it was causing some weird error when i closed programs. Housemate2 also deleted it and took my problem as an excuse.

We have thought about getting a router, but housemate2 doesn't want to spend any money and I'm not working atm and neither is housemate3.

Is there a way i could tamper with housemate2's bandwidth and limit it without using some obvious program he could simply deactivate? He's pretty much a computer noob, he knows a bit and stuff... I'm not looking into hacking him or damaging or making irreversible changes. I just don't want to fight over cable, he's a good friend but a bit stubborn at times.

Thanks for your help.

 

Thanks for the reply, will try those out.