I downloaded the Windows 7 beta .iso file from Microsoft and spun up a VMWare virtual machine to give it a test drive. As it turns out, it likes to nag you about AV.
The software prompts you (you look so skinny, you should eat something kind of nagging) to let you know that you might want to put some antivirus software on this puppy before the evil Internets come and attack you. As always, Microsoft is quick to point out how you're failing to be secure.
Just one small problem with that - it's beginning to look like a bunch of the major AV vendors haven't gotten around to supporting Windows 7 yet, not surprising since it is beta software. Still.
So far, it looks like McAfee Total Protection is a no-go, and Norton seems to throw errors for some when run on Windows 7. I use Kapersky myself, which seems to work fine, and I've heard through the security grapevine that AVG works as well.
Keep this is mind if you decide to play with the beta version, and as always, use caution if you decide to run Windows 7 on a box with direct Internet access. If you're able to run it sandboxed in a VM, all the better, but that limits testing and functionality.
If you're silly enough to run the beta in a production environment, or do any sort of network or file sharing between Windows 7 and live data, I look forward to reading your terrible story that is sure to be reported on one of the myriad security blogs.