Fire wall setting suggestions

Just found out i don,t have firewall set after 3 years,i an running 10.6.3 i download torrent files occasionally,on internet,. ilooked at settings options and not sure what to select.
Use firefox and Safari.,also have air port express.

Keep it off, really no need for it to be on, it's also the reason Apple ships its products with it turned off by default.

HTH,
- Simon