GNU GPL Antivirus software

Technically according to the license agreement it is NOT illegal to use it for a business. The large issue is that Microsoft will not provide "support" for anyone but home users or home-based businesses. But it never states you can not use it other places. We here at my office use it but we are a smaller company at just under 40 people. We switched from Avast as it became rather annoying and was letting by a fair amount of rogue av's.

I'm about 99% sure there are no free for business use antivirus software. All the free ones are only for personal use only.

If you decide to use a free antivirus software you should take your time reading the terms and conditions. Because if the terms say no business use and you are a business the company that owns the software could technically sue your company. The chances are slim, but assume the company runs a report on users updating software. They notice 100's or 1000's of computers are getting updates from there repository from the same location. They might seek legal action. However, the chances are slim, because locations suck a libraries, schools, large businesses where that provide free wifi, etc..... would all appear the same.

So in short read the terms and to really be safe contact the company providing the software. Ask, if a business can use the software. If so does it just mean you forfeit support?

You just want to cover yourself and the company you work for. As I see it telling your boss "There is no free software" so you have these choices..... Here are the pros and here are the cons......

The use of Microsoft Security Essentials in ANY organisation on MORE than ten computers breaks the terms of the lisence so what scissors85 is advising you if wrong.

From  http://blogs.msdn.com/b/mssmallbiz/archive/2010/09/22/announcing-microsoft-security-essentials-available-free-to-small-businesses-in-october.aspx

For those reasons, we are extremely excited today to let you know that Microsoft is making its Microsoft Security Essentials available to small businesses on up to 10 PCs for FREE, beginning in early October!  By providing Microsoft Security Essentials to small businesses free of charge, Microsoft extends its commitment to help these companies save money and grow their business by offering no-cost protection from viruses, spyware and other malicious threats.

@Neilsr All I have to say is WOW at Microsoft. So they claim the MSE solution is for small businesses of up to 10 PC's. Name a company that has an office with 10 or less employees considering everyone has a computer. Microsoft is using a crude tactic by having a good AV but not offering it to businesses. Instead they suggest going with MS Forefront...but it costs and it's not cheap. It's too bad too because MSE is a god solution.

Apparently I can't type...I mean to say good solution not god. Also when I mention office I mean a company that resides in a building and not out of their homes. We are considering a small company at just under 40 employees. Basically, for Microsoft to say a small business consists of 10 or less employees is just sad. If the number was 15-25 that would be much more acceptable and real. But 10 is highly unlikely.

Yes but they are a Business!! They are their to make money not GIVE IT AWAY :D

And yes I know of lots of small businesses with 10 or less PC's

In short do yourself a favor, BUY a decent antimalware solution.  It will cost less in the long run (if you really want to look at costs, just figure the amount of time lost due to virus infections as manhours and multiply by your average hourly salary rate and then by the number of employees in the business, timelost x average hourly rate x number of employees - that doesn't even count the amount of time spent disinfecting or reimaging computers).  

Thanks!