*Cough*
Windows already has a Firewall, if I am trusting there security service (which has worked better then the paid service...i.e no false reporting of files as viruses when they aren't and accurate spotting of real threats.) I think I can trust their firewall. But I can understand if you don't want to use the program. Just putting what I use out there.
I don't really know what you mean by spam filter...email spam? Cause my Gmail catches that by itself.