Anti virus software

[dave101]

I've voted for AVG but my real choice is Avast... wondering why its not included in the choice. For me it the best.

[tbirdtbird]

For those techies out there you might want to check out this site, which is very trustworthy:
http://www.majorgeeks.com/
As far as virus scanners, I'm with Paul. The free versions of these have to be updated manually but they are very good:
http://www.superantispyware.com/
http://www.malwarebytes.org/mbam.php
I run these weekly.
For my real time scanner I use Webroot Spysweeper
http://www.webroot.com/En_US/consumer-products.html
get the 39.95 version, that is all you need. When you renew you can get the CD for another $5-6 but you don't need it. Although it is real-time, you should run a full scan weekly also, and it can be set to do that automatically if desired.
I'd also run Spybot as mentioned
http://www.safer-networking.org/en/download/
These recommendations are from techie friends who do this for a living. You definitely need to run more than one scanner.
If you have your business and finances on a computer, I would highly advise that you never go on-line with that computer, instead use a separate computer for on-line activities.
You should also consider cleaning your machine weekly using this (but don't use the registry cleaner utility):
http://www.piriform.com/ccleaner
Set it to automatically update, and clean before you scan, that way scanning will be faster.