Kaspersky is letting you scan your drives for free. no real time protection or virus removal. http://www.kaspersky.com/virusscanner
If you have Comcast as your ISP they will give you McAfee for free. I use McAfee Security Center that I got from them for free. They also offer a couple other McAfee programs. You might be able to get it for free if you just know someone that has Comcast. I think anyone with a Comcast email address can get it. If you have a Comcast friend, they can make an email address for you.
Once you install Norton or McAfee good luck being able to get it off your hard drive! I had to threaten Symentac with malicous posts on the internet to get them to help me to remove the embedded files. Norton is shit, my friend was using it and his computer was full of viruses that brought his machine done eventually. An IT guy suggested Kapersky and now all seems well.
I have been using Norton products for years, but have not paid full price for one in a long time. Every year someplace offers one of their products "free after rebates" which always includes a substantial upgrade rebate. It is a pain cutting up boxes and filing rebates, and you do pay sales tax, but it is better than laying out $30 each year. I usually get Norton Internet securities which contains the anti virus as well as firewall protection. Systemworks gives you other utilities as well. They can also be found cheaper on ebay, particularly when getting previous years versions that still give you a years worth of updating. I certainly won't brag on the merits of Norton as they have deteriorated in the past few years. But, it is better than no protection at all. Download.com is a good place to look if you want something else.
Google this: Windows Live Onecare. This is apparently a one-stop security solution. Looks good. Anyone have any experience with this? I don't think many people are aware of this yet. Always amusing to me when I read these posts where people can't seem to justify spending such a small fee for computer protection. Wonder how much they pay for auto insurance??
Be careful with McAfee rebate program, they've only send me checks less than half the times. One other time, they said there are missing items (they don't say which) while I sent in everything very carefully. I don't know why they are doing this if they can't honor it. I will not buy from them again.
Bit Defender and Nod32 are hands down the best antivirus programs, that the average user will never know about. I use Bit Defender now since my Nod32 ended, but I'm thinking about going back to it, I didn't have SINGLE virus with Nod32, and I actually didn't have to reinstall my OS for 6 months straight, and I used to reinstall every other month. ESET created a great product with Nod32, love it. These are not free, but, you get what you pay for, and these are worth it if you have money, if not, why are you on a trading website, hehe.