I'm using FF w/ Ghostery and NoScript for privacy and security.
I think there are loopholes as Pelican recognizes my id when reopening a page. Probably static IP.
I use Malwarebytes, but its been a bit buggy and intrusive at times.
No problems so far that I'm aware of.
I also use
CCleaner - PC Optimization and Cleaning - Free Download for maintenance, which also has a registry cleanup feature.
There are probably better dedicated programs out there.
I stopped using MS Security Essentials because it no longer supports Win XP.
Win7 was a step backwards from WinXP.
Win8 was made for 8 year olds not business.