Win7 has been out of support for a while. You have bigger issues than AV. I can tell you with certainty that Win7 can be compromise regardless of AV or antimalware.
Do I use W7 for internet banking, financial matters, that kind of stuff? No.
Do I use it because Adobe Acrobat 10 and Photoshop CS5 are my preferred Adobe programs for PDF and picture files and they work better under Windows 7, as well as other programs I use? Yes.
The newer operating systems all suck, they're all subscription based now, and I actually own my programs and they are much simpler to use.
In the end, though, it all boils down to this: Windows 7 was created to be controlled by the user, but everything afterwards was created to be controlled by corporations. I will never that happen, and when I get to the point where I don't need either O/S I will migrate to Linux and completely cut ties with Microsoft.