Rate Limiting w/ Class Based Queuing?

fwerked asks: "I have recently been commissioned by the uppers in my company to produce rate limiting system for a college apartment complex with 600 users. I am hoping to use a Linux system to limit each users rate to 128 Mb. using Class Based Queuing. In addition I will need to route, DHCP, and NAT. I was hoping there was someone out there in the Slashdot community that has implemented this on a large scale that might be able to recommend hardware specs (CPU, RAM, etc) and if these services should be divided among several boxes or dumped on one bad boy."