Anti-virus and Firewall are very important protection for all systems, home or business.
If you don't have a budget to purchase software, there are some excellent free programs available. Please note that I am only going to be discussing Windows in this post, as Mac or Linux AV is a completely different subject worthy of a future blog post.
The first product you should consider is ZoneAlarm Antivirus+Firewall. This lightweight combination is perfect to maximize protection while minimizing performance impact.
However, if you do not want a combination Antivirus+Firewall, it's perfectly acceptable to use ZoneAlarm's standalone firewall product with another antivirus product...but I strongly recommend at a minimum using ZoneAlarm's firewall, as I have yet to find a comparable firewall product for free.
If you're looking for an alternative to ZoneAlarm's antivirus, there are many available.
First on the list is AVG (which you can download directly here)
Second is Microsoft Security Essentials, which requires a legitimately licensed copy of Windows
Third is ClamWin, an open source antivirus program which is extremely lightweight but does not feature an on-access scanner.
If you have a budget to afford antivirus at home, or need to protect your business, VIPRE has written a guide on choosing the right antivirus solution for your business.
By the way, if you'd like to support this blog, feel free to make a purchase through our Software Catalog.