For a home user something like the Linksys BEFSR41 in it's default configuration is ample sufficient protection from malicious ingress for a low cost and a simple installation.
Yep, and to go a step farther, this particular device has a configuration screen where it will interoperate with Zone Alarm or BlackIce. I use this model along with one of the previous personal firewalls. Top that with the logviewer proggie that Linksys provides from their FTP site and you have a nice little setup for a home network.

One interesting thing about this model is that a few firmware revs back, it had a stateful packet inspection option that mysteriously vanished at around the same time a newer model of the router came out. Hmmmm. LOL

--TH13