I have been using Ubunti exclusivey for about a year, year and a half or something like that.
I don’t use VM. I don’t have any Windows OS at all any more.
It ha something called “Clamshell” anti-virus and I have no idea about firewalls. Maybe Shadow knows
The Shadow always knows! :D
I run Windows 7 inside a VM on my linux laptop (8G RAM) without issues.
There are several AV products that will run under Linux--however, most are just to prevent virii from being passed on to Windows boxes. There really is not much need at this time to run any anti-virus. Getting run to run at startup is a no-brainer, though. What GeronL meant, though, is ClamAV. It comes standard with most distributions, if you wish to install it.
The same goes for firewalls. They come included with standard repositories. And I do recommend running a firewall. Newer Fedora distros run firewalld to take the place of older iptables and ip6tables.
Hope that helps!