Whether you are on dial-up or directly connected to the Internet through your local cable company there is always a chance of viruses and spam coming through without a firewall. It really depends on how much surfing you and what you use your computer for. In my opinion, there is less chance of getting hit if you are on a dial-up.

At work all of our local office do have a firewall because their ISP is either the telephone company or cable company and they are connected 24/7.

At home, I'm connected with high-speed though my cable company and I do not have a firewall. I know I'm taking a chance but I only use my computer for email and Pet Talk. If something were to happen I would not lose anything by reformatting the hard drive and starting over.

Up here firewalls are cheap to buy and easy to install.