File/Print Sharing and Broadband??

Okay...Question, here. Everything I'm reading says we should disable the file and print sharing on our home network because we have broadband now. But how the heck do we use our systems as a network without it? We can't map network drives without sharing, and the password protection for various devices doesn't seem to be working; I was able to click my shortcut to the other computer's hard drive and get right to it with no password entry required. Grrrrr!