It's not a stupid question. You just don't know too much about computers. What security do you have on your wireless router? Make sure you don't have WEP. WEP can be cracked with the write program very easily. It is a very weak encryption. It also only runs in 54 mpbs which is very slow. I suggest:
"WPA2-PSK [AES]" security. That can run up to 300 mpbs. As far as torrents go, be weary.
You should get:
Download PeerBlock 1.1 Whenever you download a torrent make sure it is up. The last thing you want is to receive a letter from the government and then your ISP threatens to drop your service. The chances of that happening are slim but the possibility is still there. If another user manages to get into your network they can only view your logs. They can't spy on you and see exactly what you're doing on the computer. Worst case is they can view your history from the logs as I just mentioned. The logs will show them all the past websites you were on and internal IP's.