No doubt you will have read all the stories in the press about the 'zombie' PCs round the world spending every moment sending spam and trying to crack credit card accounts. What they dont tell you is that it is extremely easy to protect your PC using Zonealarm. The free version will be an effective firewall for your PC, the paid for 'pro' version (about $70) will give you effective antivirus protection as well.

www.zonelabs.com (PC only)

And if you fancy web browsing and email which is smaller and faster (as well as less accident prone on the security front than many big names:-) ) try Mozilla.

www.mozilla.org

Firefox is the web-browser, Thunderbird is their e-mail and usenet news client, both are small, fast and stable and will work on Mac OSX, Windows and Linux.