Forefront Endpoint is not compatible for Windows 8.

What else does Microsoft offer as an antivirus for Windows 8 Machines?

Or do they have a version compatible for Windows 8?

Windows 8 already includes Windows Defender which is basically MSE.

Thank you :)

Hi,

Here it is our official answer for that:
http://blogs.technet.com/b/mmpc/archive/2013/10/09/our-commitment-to-microsoft-antimalware.aspx

You can understand more from this : 

Goodbye Microsoft Security Essentials: Microsoft Now Recommends You Use a Third-Party Antivirus

I am a naive user and just bought a new PC.  So, with Windows Defender or MSE, does that mean I don't need to install McAfee or Symantec?