I just installed Windows 8 on my other hard drive, now I have dual boot with Windows 7. I was going to add Avast to it but Windows Defender and Windows Firewall is doing fantastic, so why change when something is working that good?
So I would recommend keeping Windows Defender with the default UAC setting, you can however add a layer protection with Malwarebytes Pro, Sandboxie and some browser security extensions like WOT, LastPass, etc.
I really don't think malware can get past UAC, unless you allow it to.
Just watch and only allow processes that you know are safe.
If you use UAC to its full potential by always reading and paying attention, it will not fail you.
The SmartScreen on IE10 is also very good but doesn't get everything.
Don't download files that are not known to be safe. IE10 is the first version that I don't mind using. Google Chrome runs extremely light on Windows 8, still probably the best choice for default browser.
Enjoy!!
