The research itself is trustworthy but it doesn't account for the number of changes that can happen. As we speak new kinds of online threats are being developed to try and infiltrate your computer. That's why users need to update their system and their security.
You really need to do those updates if you want to keep your computer safe. As I've stressed in, My PC Tweaks, the threats to your computer change with alarming frequency. People who develop malware for their own personal gain get craftier every day. You don't want to find that your newly installed Windows 7 has now become a virus ridden operating system.
So if you want to keep yourself safe, you can opt to install antivirus software, keep your system updated or just keep out of really questionable sites.
There are some changes to the way that 7's firewall system works but then that might not be enough to keep your computer secured. There's a lot of free antivirus download links out on the web and it would be okay to try one, just remember to download it from a reputable site. Check on the comments or reviews for a certain piece of software before you download it. If you can do this then you'll be all right.
Windows 7 is still pretty vulnerable, but you can keep your PC safe nonetheless.